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[PATCH v3 2/7] zram: fix double free backing device

by Minchan Kim

If blkdev_get fails, we shouldn't do blkdev_put. Otherwise, kernel emits below log. This patch fixes it. [ 31.073006] WARNING: CPU: 0 PID: 1893 at fs/block_dev.c:1828 blkdev_put+0x105/0x120 [ 31.075104] Modules linked in: [ 31.075898] CPU: 0 PID: 1893 Comm: swapoff Not tainted 4.19.0+ #453 [ 31.077484] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 31.079589] RIP: 0010:blkdev_put+0x105/0x120 [ 31.080606] Code: 48 c7 80 a0 00 00 00 00 00 00 00 48 c7 c7 40 e7 40 96 e8 6e 47 73 00 48 8b bb e0 00 00 00 e9 2c ff ff ff 0f 0b e9 75 ff ff ff <0f> 0b e9 5a ff ff ff 48 c7 80 a0 00 00 00 00 00 00 00 eb 87 0f 1f [ 31.085080] RSP: 0018:ffffb409005c7ed0 EFLAGS: 00010297 [ 31.086383] RAX: ffff9779fe5a8040 RBX: ffff9779fbc17300 RCX: 00000000b9fc37a4 [ 31.088105] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff9640e740 [ 31.089850] RBP: ffff9779fbc17318 R08: ffffffff95499a89 R09: 0000000000000004 [ 31.091201] R10: ffffb409005c7e50 R11: 7a9ef6088ff4d4a1 R12: 0000000000000083 [ 31.092276] R13: ffff9779fe607b98 R14: 0000000000000000 R15: ffff9779fe607a38 [ 31.093355] FS: 00007fc118d9b840(0000) GS:ffff9779fc600000(0000) knlGS:0000000000000000 [ 31.094582] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.095541] CR2: 00007fc11894b8dc CR3: 00000000339f6001 CR4: 0000000000160ef0 [ 31.096781] Call Trace: [ 31.097212] __x64_sys_swapoff+0x46d/0x490 [ 31.097914] do_syscall_64+0x5a/0x190 [ 31.098550] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.099402] RIP: 0033:0x7fc11843ec27 [ 31.100013] Code: 73 01 c3 48 8b 0d 71 62 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 41 62 2c 00 f7 d8 64 89 01 48 [ 31.103149] RSP: 002b:00007ffdf69be648 EFLAGS: 00000206 ORIG_RAX: 00000000000000a8 [ 31.104425] RAX: ffffffffffffffda RBX: 00000000011d98c0 RCX: 00007fc11843ec27 [ 31.105627] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 00000000011d98c0 [ 31.106847] RBP: 0000000000000001 R08: 00007ffdf69be690 R09: 0000000000000001 [ 31.108038] R10: 00000000000002b1 R11: 0000000000000206 R12: 0000000000000001 [ 31.109231] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 31.110433] irq event stamp: 4466 [ 31.111001] hardirqs last enabled at (4465): [<ffffffff953ebd43>] __free_pages_ok+0x1e3/0x490 [ 31.112437] hardirqs last disabled at (4466): [<ffffffff95201b7a>] trace_hardirqs_off_thunk+0x1a/0x1c [ 31.113973] softirqs last enabled at (3420): [<ffffffff95e00333>] __do_softirq+0x333/0x446 [ 31.115364] softirqs last disabled at (3407): [<ffffffff9527aee1>] irq_exit+0xd1/0xe0 Cc: stable(a)vger.kernel.org # 4.14+ Signed-off-by: Minchan Kim <minchan(a)kernel.org> --- drivers/block/zram/zram_drv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 21a7046958a3..d1459cc1159f 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -387,8 +387,10 @@ static ssize_t backing_dev_store(struct device *dev, bdev = bdgrab(I_BDEV(inode)); err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram); - if (err < 0) + if (err < 0) { + bdev = NULL; goto out; + } nr_pages = i_size_read(inode) >> PAGE_SHIFT; bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long); -- 2.20.0.rc0.387.gc7a69e6b6c-goog

7 years

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[PATCH] drm/amdgpu: don't expose fan attributes on APUs

by Alex Deucher

They don't have a fan controller. Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Cc: stable(a)vger.kernel.org --- drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c index 0de8650c5d6e..1f61ed95727c 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c @@ -1644,6 +1644,19 @@ static umode_t hwmon_attributes_visible(struct kobject *kobj, attr == &sensor_dev_attr_fan1_enable.dev_attr.attr)) return 0; + /* Skip fan attributes on APU */ + if ((adev->flags & AMD_IS_APU) && + (attr == &sensor_dev_attr_pwm1.dev_attr.attr || + attr == &sensor_dev_attr_pwm1_enable.dev_attr.attr || + attr == &sensor_dev_attr_pwm1_max.dev_attr.attr || + attr == &sensor_dev_attr_pwm1_min.dev_attr.attr || + attr == &sensor_dev_attr_fan1_input.dev_attr.attr || + attr == &sensor_dev_attr_fan1_min.dev_attr.attr || + attr == &sensor_dev_attr_fan1_max.dev_attr.attr || + attr == &sensor_dev_attr_fan1_target.dev_attr.attr || + attr == &sensor_dev_attr_fan1_enable.dev_attr.attr)) + return 0; + /* Skip limit attributes if DPM is not enabled */ if (!adev->pm.dpm_enabled && (attr == &sensor_dev_attr_temp1_crit.dev_attr.attr || -- 2.13.6

7 years

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+ zram-writeback-throttle.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: writeback throttle has been added to the -mm tree. Its filename is zram-writeback-throttle.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-writeback-throttle.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-writeback-throttle.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: writeback throttle On small memory systems there are lots of write IOs so if we use a flash device as swap there would be serious flash wearout. To overcome this problem, system developers need to design a write limitation strategy to guarantee flash health for the entire product life. This patch creates a new knob "writeback_limit" on zram. With that, if the current writeback IO count (/sys/block/zramX/io_stat) exceeds the limitation, zram stops further writeback until the admin can reset the limit. Link: http://lkml.kernel.org/r/20181127055429.251614-8-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Cc: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- Documentation/ABI/testing/sysfs-block-zram | 9 +++ Documentation/blockdev/zram.txt | 2 drivers/block/zram/zram_drv.c | 47 ++++++++++++++++++- drivers/block/zram/zram_drv.h | 2 4 files changed, 59 insertions(+), 1 deletion(-) --- a/Documentation/ABI/testing/sysfs-block-zram~zram-writeback-throttle +++ a/Documentation/ABI/testing/sysfs-block-zram @@ -121,3 +121,12 @@ Description: The bd_stat file is read-only and represents backing device's statistics (bd_count, bd_reads, bd_writes) in a format similar to block layer statistics file format. + +What: /sys/block/zram<id>/writeback_limit +Date: November 2018 +Contact: Minchan Kim <minchan(a)kernel.org> +Description: + The writeback_limit file is read-write and specifies the maximum + amount of writeback ZRAM can do. The limit could be changed + in run time and "0" means disable the limit. + No limit is the initial state. --- a/Documentation/blockdev/zram.txt~zram-writeback-throttle +++ a/Documentation/blockdev/zram.txt @@ -164,6 +164,8 @@ reset WO trigger device r mem_used_max WO reset the `mem_used_max' counter (see later) mem_limit WO specifies the maximum amount of memory ZRAM can use to store the compressed data +writeback_limit WO specifies the maximum amount of write IO zram can + write out to backing device as 4KB unit max_comp_streams RW the number of possible concurrent compress operations comp_algorithm RW show and change the compression algorithm compact WO trigger memory compaction --- a/drivers/block/zram/zram_drv.c~zram-writeback-throttle +++ a/drivers/block/zram/zram_drv.c @@ -330,6 +330,40 @@ next: } #ifdef CONFIG_ZRAM_WRITEBACK + +static ssize_t writeback_limit_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + u64 val; + ssize_t ret = -EINVAL; + + if (kstrtoull(buf, 10, &val)) + return ret; + + down_read(&zram->init_lock); + atomic64_set(&zram->stats.bd_wb_limit, val); + if (val == 0 || val > atomic64_read(&zram->stats.bd_writes)) + zram->stop_writeback = false; + up_read(&zram->init_lock); + ret = len; + + return ret; +} + +static ssize_t writeback_limit_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + u64 val; + struct zram *zram = dev_to_zram(dev); + + down_read(&zram->init_lock); + val = atomic64_read(&zram->stats.bd_wb_limit); + up_read(&zram->init_lock); + + return scnprintf(buf, PAGE_SIZE, "%llu\n", val); +} + static void reset_bdev(struct zram *zram) { struct block_device *bdev; @@ -571,6 +605,7 @@ static ssize_t writeback_store(struct de char mode_buf[8]; unsigned long mode = -1UL; unsigned long blk_idx = 0; + u64 wb_count, wb_limit; sz = strscpy(mode_buf, buf, sizeof(mode_buf)); if (sz <= 0) @@ -612,6 +647,11 @@ static ssize_t writeback_store(struct de bvec.bv_len = PAGE_SIZE; bvec.bv_offset = 0; + if (zram->stop_writeback) { + ret = -EIO; + break; + } + if (!blk_idx) { blk_idx = alloc_block_bdev(zram); if (!blk_idx) { @@ -670,7 +710,7 @@ static ssize_t writeback_store(struct de continue; } - atomic64_inc(&zram->stats.bd_writes); + wb_count = atomic64_inc_return(&zram->stats.bd_writes); /* * We released zram_slot_lock so need to check if the slot was * changed. If there is freeing for the slot, we can catch it @@ -694,6 +734,9 @@ static ssize_t writeback_store(struct de zram_set_element(zram, index, blk_idx); blk_idx = 0; atomic64_inc(&zram->stats.pages_stored); + wb_limit = atomic64_read(&zram->stats.bd_wb_limit); + if (wb_limit != 0 && wb_count >= wb_limit) + zram->stop_writeback = true; next: zram_slot_unlock(zram, index); } @@ -1767,6 +1810,7 @@ static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK static DEVICE_ATTR_RW(backing_dev); static DEVICE_ATTR_WO(writeback); +static DEVICE_ATTR_RW(writeback_limit); #endif static struct attribute *zram_disk_attrs[] = { @@ -1782,6 +1826,7 @@ static struct attribute *zram_disk_attrs #ifdef CONFIG_ZRAM_WRITEBACK &dev_attr_backing_dev.attr, &dev_attr_writeback.attr, + &dev_attr_writeback_limit.attr, #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, --- a/drivers/block/zram/zram_drv.h~zram-writeback-throttle +++ a/drivers/block/zram/zram_drv.h @@ -86,6 +86,7 @@ struct zram_stats { atomic64_t bd_count; /* no. of pages in backing device */ atomic64_t bd_reads; /* no. of reads from backing device */ atomic64_t bd_writes; /* no. of writes from backing device */ + atomic64_t bd_wb_limit; /* writeback limit of backing device */ #endif }; @@ -113,6 +114,7 @@ struct zram { */ bool claim; /* Protected by bdev->bd_mutex */ struct file *backing_dev; + bool stop_writeback; #ifdef CONFIG_ZRAM_WRITEBACK struct block_device *bdev; unsigned int old_block_size; _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

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+ zram-add-bd_stat-statistics.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: add bd_stat statistics has been added to the -mm tree. Its filename is zram-add-bd_stat-statistics.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-add-bd_stat-statistics.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-add-bd_stat-statistics.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: add bd_stat statistics bd_stat represents things that happened in the backing device. Currently it supports bd_counts, bd_reads and bd_writes which are helpful to understand wearout of flash and memory saving. Link: http://lkml.kernel.org/r/20181127055429.251614-7-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Cc: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- Documentation/ABI/testing/sysfs-block-zram | 8 +++++ Documentation/blockdev/zram.txt | 11 +++++++ drivers/block/zram/zram_drv.c | 29 +++++++++++++++++++ drivers/block/zram/zram_drv.h | 5 +++ 4 files changed, 53 insertions(+) --- a/Documentation/ABI/testing/sysfs-block-zram~zram-add-bd_stat-statistics +++ a/Documentation/ABI/testing/sysfs-block-zram @@ -113,3 +113,11 @@ Contact: Minchan Kim <minchan(a)kernel.org Description: The writeback file is write-only and trigger idle and/or huge page writeback to backing device. + +What: /sys/block/zram<id>/bd_stat +Date: November 2018 +Contact: Minchan Kim <minchan(a)kernel.org> +Description: + The bd_stat file is read-only and represents backing device's + statistics (bd_count, bd_reads, bd_writes) in a format + similar to block layer statistics file format. --- a/Documentation/blockdev/zram.txt~zram-add-bd_stat-statistics +++ a/Documentation/blockdev/zram.txt @@ -221,6 +221,17 @@ line of text and contains the following pages_compacted the number of pages freed during compaction huge_pages the number of incompressible pages +File /sys/block/zram<id>/bd_stat + +The stat file represents device's backing device statistics. It consists of +a single line of text and contains the following stats separated by whitespace: + bd_count size of data written in backing device. + Unit: 4K bytes + bd_reads the number of reads from backing device + Unit: 4K bytes + bd_writes the number of writes to backing device + Unit: 4K bytes + 9) Deactivate: swapoff /dev/zram0 umount /dev/zram1 --- a/drivers/block/zram/zram_drv.c~zram-add-bd_stat-statistics +++ a/drivers/block/zram/zram_drv.c @@ -502,6 +502,7 @@ retry: if (test_and_set_bit(blk_idx, zram->bitmap)) goto retry; + atomic64_inc(&zram->stats.bd_count); return blk_idx; } @@ -511,6 +512,7 @@ static void free_block_bdev(struct zram was_set = test_and_clear_bit(blk_idx, zram->bitmap); WARN_ON_ONCE(!was_set); + atomic64_dec(&zram->stats.bd_count); } static void zram_page_end_io(struct bio *bio) @@ -668,6 +670,7 @@ static ssize_t writeback_store(struct de continue; } + atomic64_inc(&zram->stats.bd_writes); /* * We released zram_slot_lock so need to check if the slot was * changed. If there is freeing for the slot, we can catch it @@ -757,6 +760,7 @@ static int read_from_bdev_sync(struct zr static int read_from_bdev(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *parent, bool sync) { + atomic64_inc(&zram->stats.bd_reads); if (sync) return read_from_bdev_sync(zram, bvec, entry, parent); else @@ -1013,6 +1017,25 @@ static ssize_t mm_stat_show(struct devic return ret; } +#ifdef CONFIG_ZRAM_WRITEBACK +static ssize_t bd_stat_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct zram *zram = dev_to_zram(dev); + ssize_t ret; + + down_read(&zram->init_lock); + ret = scnprintf(buf, PAGE_SIZE, + "%8llu %8llu %8llu\n", + (u64)atomic64_read(&zram->stats.bd_count), + (u64)atomic64_read(&zram->stats.bd_reads), + (u64)atomic64_read(&zram->stats.bd_writes)); + up_read(&zram->init_lock); + + return ret; +} +#endif + static ssize_t debug_stat_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -1033,6 +1056,9 @@ static ssize_t debug_stat_show(struct de static DEVICE_ATTR_RO(io_stat); static DEVICE_ATTR_RO(mm_stat); +#ifdef CONFIG_ZRAM_WRITEBACK +static DEVICE_ATTR_RO(bd_stat); +#endif static DEVICE_ATTR_RO(debug_stat); static void zram_meta_free(struct zram *zram, u64 disksize) @@ -1759,6 +1785,9 @@ static struct attribute *zram_disk_attrs #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, +#ifdef CONFIG_ZRAM_WRITEBACK + &dev_attr_bd_stat.attr, +#endif &dev_attr_debug_stat.attr, NULL, }; --- a/drivers/block/zram/zram_drv.h~zram-add-bd_stat-statistics +++ a/drivers/block/zram/zram_drv.h @@ -82,6 +82,11 @@ struct zram_stats { atomic_long_t max_used_pages; /* no. of maximum pages stored */ atomic64_t writestall; /* no. of write slow paths */ atomic64_t miss_free; /* no. of missed free */ +#ifdef CONFIG_ZRAM_WRITEBACK + atomic64_t bd_count; /* no. of pages in backing device */ + atomic64_t bd_reads; /* no. of reads from backing device */ + atomic64_t bd_writes; /* no. of writes from backing device */ +#endif }; struct zram { _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

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+ zram-support-idle-huge-page-writeback.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: support idle/huge page writeback has been added to the -mm tree. Its filename is zram-support-idle-huge-page-writeback.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-support-idle-huge-page-writeb… and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-support-idle-huge-page-writeb… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: support idle/huge page writeback Add a new feature "zram idle/huge page writeback". In the zram-swap use case, zram usually has many idle/huge swap pages. It's pointless to keep them in memory (ie, zram). To solve this problem, this feature introduces idle/huge page writeback to the backing device so the goal is to save more memory space on embedded systems. Normal sequence to use idle/huge page writeback feature is as follows, while (1) { # mark allocated zram slot to idle echo all > /sys/block/zram0/idle # leave system working for several hours # Unless there is no access for some blocks on zram, # they are still IDLE marked pages. echo "idle" > /sys/block/zram0/writeback or/and echo "huge" > /sys/block/zram0/writeback # write the IDLE or/and huge marked slot into backing device # and free the memory. } By per discussion: https://lore.kernel.org/lkml/20181122065926.GG3441@jagdpanzerIV/T/#u, This patch removes direct incommpressibe page writeback feature (d2afd25114f4 ("zram: write incompressible pages to backing device")) so we could regard it as regression because incompressible pages don't go to backing storage automatically. Instead, users should do this via "echo huge" > /sys/block/zram/writeback" manually. If we hear some regression, we could restore the function. Link: http://lkml.kernel.org/r/20181127055429.251614-6-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Reviewed-by: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- Documentation/ABI/testing/sysfs-block-zram | 7 Documentation/blockdev/zram.txt | 28 +- drivers/block/zram/Kconfig | 5 drivers/block/zram/zram_drv.c | 247 +++++++++++++------ drivers/block/zram/zram_drv.h | 1 5 files changed, 209 insertions(+), 79 deletions(-) --- a/Documentation/ABI/testing/sysfs-block-zram~zram-support-idle-huge-page-writeback +++ a/Documentation/ABI/testing/sysfs-block-zram @@ -106,3 +106,10 @@ Description: idle file is write-only and mark zram slot as idle. If system has mounted debugfs, user can see which slots are idle via /sys/kernel/debug/zram/zram<id>/block_state + +What: /sys/block/zram<id>/writeback +Date: November 2018 +Contact: Minchan Kim <minchan(a)kernel.org> +Description: + The writeback file is write-only and trigger idle and/or + huge page writeback to backing device. --- a/Documentation/blockdev/zram.txt~zram-support-idle-huge-page-writeback +++ a/Documentation/blockdev/zram.txt @@ -238,11 +238,31 @@ line of text and contains the following = writeback -With incompressible pages, there is no memory saving with zram. -Instead, with CONFIG_ZRAM_WRITEBACK, zram can write incompressible page +With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page to backing storage rather than keeping it in memory. -User should set up backing device via /sys/block/zramX/backing_dev -before disksize setting. +To use the feature, admin should set up backing device via + + "echo /dev/sda5 > /sys/block/zramX/backing_dev" + +before disksize setting. It supports only partition at this moment. +If admin want to use incompressible page writeback, they could do via + + "echo huge > /sys/block/zramX/write" + +To use idle page writeback, first, user need to declare zram pages +as idle. + + "echo all > /sys/block/zramX/idle" + +From now on, any pages on zram are idle pages. The idle mark +will be removed until someone request access of the block. +IOW, unless there is access request, those pages are still idle pages. + +Admin can request writeback of those idle pages at right timing via + + "echo idle > /sys/block/zramX/writeback" + +With the command, zram writeback idle pages from memory to the storage. = memory tracking --- a/drivers/block/zram/Kconfig~zram-support-idle-huge-page-writeback +++ a/drivers/block/zram/Kconfig @@ -15,7 +15,7 @@ config ZRAM See Documentation/blockdev/zram.txt for more information. config ZRAM_WRITEBACK - bool "Write back incompressible page to backing device" + bool "Write back incompressible or idle page to backing device" depends on ZRAM help With incompressible page, there is no memory saving to keep it @@ -23,6 +23,9 @@ config ZRAM_WRITEBACK For this feature, admin should set up backing device via /sys/block/zramX/backing_dev. + With /sys/block/zramX/{idle,writeback}, application could ask + idle page's writeback to the backing device to save in memory. + See Documentation/blockdev/zram.txt for more information. config ZRAM_MEMORY_TRACKING --- a/drivers/block/zram/zram_drv.c~zram-support-idle-huge-page-writeback +++ a/drivers/block/zram/zram_drv.c @@ -52,6 +52,9 @@ static unsigned int num_devices = 1; static size_t huge_class_size; static void zram_free_page(struct zram *zram, size_t index); +static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, + u32 index, int offset, struct bio *bio); + static int zram_slot_trylock(struct zram *zram, u32 index) { @@ -73,13 +76,6 @@ static inline bool init_done(struct zram return zram->disksize; } -static inline bool zram_allocated(struct zram *zram, u32 index) -{ - - return (zram->table[index].flags >> (ZRAM_FLAG_SHIFT + 1)) || - zram->table[index].handle; -} - static inline struct zram *dev_to_zram(struct device *dev) { return (struct zram *)dev_to_disk(dev)->private_data; @@ -138,6 +134,13 @@ static void zram_set_obj_size(struct zra zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size; } +static inline bool zram_allocated(struct zram *zram, u32 index) +{ + return zram_get_obj_size(zram, index) || + zram_test_flag(zram, index, ZRAM_SAME) || + zram_test_flag(zram, index, ZRAM_WB); +} + #if PAGE_SIZE != 4096 static inline bool is_partial_io(struct bio_vec *bvec) { @@ -308,10 +311,14 @@ static ssize_t idle_store(struct device } for (index = 0; index < nr_pages; index++) { + /* + * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race. + * See the comment in writeback_store. + */ zram_slot_lock(zram, index); - if (!zram_allocated(zram, index)) + if (!zram_allocated(zram, index) || + zram_test_flag(zram, index, ZRAM_UNDER_WB)) goto next; - zram_set_flag(zram, index, ZRAM_IDLE); next: zram_slot_unlock(zram, index); @@ -546,6 +553,158 @@ static int read_from_bdev_async(struct z return 1; } +#define HUGE_WRITEBACK 0x1 +#define IDLE_WRITEBACK 0x2 + +static ssize_t writeback_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; + unsigned long index; + struct bio bio; + struct bio_vec bio_vec; + struct page *page; + ssize_t ret, sz; + char mode_buf[8]; + unsigned long mode = -1UL; + unsigned long blk_idx = 0; + + sz = strscpy(mode_buf, buf, sizeof(mode_buf)); + if (sz <= 0) + return -EINVAL; + + /* ignore trailing newline */ + if (mode_buf[sz - 1] == '\n') + mode_buf[sz - 1] = 0x00; + + if (!strcmp(mode_buf, "idle")) + mode = IDLE_WRITEBACK; + else if (!strcmp(mode_buf, "huge")) + mode = HUGE_WRITEBACK; + + if (mode == -1UL) + return -EINVAL; + + down_read(&zram->init_lock); + if (!init_done(zram)) { + ret = -EINVAL; + goto release_init_lock; + } + + if (!zram->backing_dev) { + ret = -ENODEV; + goto release_init_lock; + } + + page = alloc_page(GFP_KERNEL); + if (!page) { + ret = -ENOMEM; + goto release_init_lock; + } + + for (index = 0; index < nr_pages; index++) { + struct bio_vec bvec; + + bvec.bv_page = page; + bvec.bv_len = PAGE_SIZE; + bvec.bv_offset = 0; + + if (!blk_idx) { + blk_idx = alloc_block_bdev(zram); + if (!blk_idx) { + ret = -ENOSPC; + break; + } + } + + zram_slot_lock(zram, index); + if (!zram_allocated(zram, index)) + goto next; + + if (zram_test_flag(zram, index, ZRAM_WB) || + zram_test_flag(zram, index, ZRAM_SAME) || + zram_test_flag(zram, index, ZRAM_UNDER_WB)) + goto next; + + if ((mode & IDLE_WRITEBACK && + !zram_test_flag(zram, index, ZRAM_IDLE)) && + (mode & HUGE_WRITEBACK && + !zram_test_flag(zram, index, ZRAM_HUGE))) + goto next; + /* + * Clearing ZRAM_UNDER_WB is duty of caller. + * IOW, zram_free_page never clear it. + */ + zram_set_flag(zram, index, ZRAM_UNDER_WB); + /* Need for hugepage writeback racing */ + zram_set_flag(zram, index, ZRAM_IDLE); + zram_slot_unlock(zram, index); + if (zram_bvec_read(zram, &bvec, index, 0, NULL)) { + zram_slot_lock(zram, index); + zram_clear_flag(zram, index, ZRAM_UNDER_WB); + zram_clear_flag(zram, index, ZRAM_IDLE); + zram_slot_unlock(zram, index); + continue; + } + + bio_init(&bio, &bio_vec, 1); + bio_set_dev(&bio, zram->bdev); + bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9); + bio.bi_opf = REQ_OP_WRITE | REQ_SYNC; + + bio_add_page(&bio, bvec.bv_page, bvec.bv_len, + bvec.bv_offset); + /* + * XXX: A single page IO would be inefficient for write + * but it would be not bad as starter. + */ + ret = submit_bio_wait(&bio); + if (ret) { + zram_slot_lock(zram, index); + zram_clear_flag(zram, index, ZRAM_UNDER_WB); + zram_clear_flag(zram, index, ZRAM_IDLE); + zram_slot_unlock(zram, index); + continue; + } + + /* + * We released zram_slot_lock so need to check if the slot was + * changed. If there is freeing for the slot, we can catch it + * easily by zram_allocated. + * A subtle case is the slot is freed/reallocated/marked as + * ZRAM_IDLE again. To close the race, idle_store doesn't + * mark ZRAM_IDLE once it found the slot was ZRAM_UNDER_WB. + * Thus, we could close the race by checking ZRAM_IDLE bit. + */ + zram_slot_lock(zram, index); + if (!zram_allocated(zram, index) || + !zram_test_flag(zram, index, ZRAM_IDLE)) { + zram_clear_flag(zram, index, ZRAM_UNDER_WB); + zram_clear_flag(zram, index, ZRAM_IDLE); + goto next; + } + + zram_free_page(zram, index); + zram_clear_flag(zram, index, ZRAM_UNDER_WB); + zram_set_flag(zram, index, ZRAM_WB); + zram_set_element(zram, index, blk_idx); + blk_idx = 0; + atomic64_inc(&zram->stats.pages_stored); +next: + zram_slot_unlock(zram, index); + } + + if (blk_idx) + free_block_bdev(zram, blk_idx); + ret = len; + __free_page(page); +release_init_lock: + up_read(&zram->init_lock); + + return ret; +} + struct zram_work { struct work_struct work; struct zram *zram; @@ -603,57 +762,8 @@ static int read_from_bdev(struct zram *z else return read_from_bdev_async(zram, bvec, entry, parent); } - -static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, - u32 index, struct bio *parent, - unsigned long *pentry) -{ - struct bio *bio; - unsigned long entry; - - bio = bio_alloc(GFP_ATOMIC, 1); - if (!bio) - return -ENOMEM; - - entry = alloc_block_bdev(zram); - if (!entry) { - bio_put(bio); - return -ENOSPC; - } - - bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9); - bio_set_dev(bio, zram->bdev); - if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, - bvec->bv_offset)) { - bio_put(bio); - free_block_bdev(zram, entry); - return -EIO; - } - - if (!parent) { - bio->bi_opf = REQ_OP_WRITE | REQ_SYNC; - bio->bi_end_io = zram_page_end_io; - } else { - bio->bi_opf = parent->bi_opf; - bio_chain(bio, parent); - } - - submit_bio(bio); - *pentry = entry; - - return 0; -} - #else static inline void reset_bdev(struct zram *zram) {}; -static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, - u32 index, struct bio *parent, - unsigned long *pentry) - -{ - return -EIO; -} - static int read_from_bdev(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *parent, bool sync) { @@ -1006,7 +1116,8 @@ out: atomic64_dec(&zram->stats.pages_stored); zram_set_handle(zram, index, 0); zram_set_obj_size(zram, index, 0); - WARN_ON_ONCE(zram->table[index].flags & ~(1UL << ZRAM_LOCK)); + WARN_ON_ONCE(zram->table[index].flags & + ~(1UL << ZRAM_LOCK | 1UL << ZRAM_UNDER_WB)); } static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, @@ -1115,7 +1226,6 @@ static int __zram_bvec_write(struct zram struct page *page = bvec->bv_page; unsigned long element = 0; enum zram_pageflags flags = 0; - bool allow_wb = true; mem = kmap_atomic(page); if (page_same_filled(mem, &element)) { @@ -1140,21 +1250,8 @@ compress_again: return ret; } - if (unlikely(comp_len >= huge_class_size)) { + if (comp_len >= huge_class_size) comp_len = PAGE_SIZE; - if (zram->backing_dev && allow_wb) { - zcomp_stream_put(zram->comp); - ret = write_to_bdev(zram, bvec, index, bio, &element); - if (!ret) { - flags = ZRAM_WB; - ret = 1; - goto out; - } - allow_wb = false; - goto compress_again; - } - } - /* * handle allocation has 2 paths: * a) fast path is executed with preemption disabled (for @@ -1643,6 +1740,7 @@ static DEVICE_ATTR_RW(max_comp_streams); static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK static DEVICE_ATTR_RW(backing_dev); +static DEVICE_ATTR_WO(writeback); #endif static struct attribute *zram_disk_attrs[] = { @@ -1657,6 +1755,7 @@ static struct attribute *zram_disk_attrs &dev_attr_comp_algorithm.attr, #ifdef CONFIG_ZRAM_WRITEBACK &dev_attr_backing_dev.attr, + &dev_attr_writeback.attr, #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, --- a/drivers/block/zram/zram_drv.h~zram-support-idle-huge-page-writeback +++ a/drivers/block/zram/zram_drv.h @@ -47,6 +47,7 @@ enum zram_pageflags { ZRAM_LOCK = ZRAM_FLAG_SHIFT, ZRAM_SAME, /* Page consists the same element */ ZRAM_WB, /* page is stored on backing_device */ + ZRAM_UNDER_WB, /* page is under writeback */ ZRAM_HUGE, /* Incompressible page */ ZRAM_IDLE, /* not accessed page since last idle marking */ _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

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0
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+ zram-introduce-zram_idle-flag.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: introduce ZRAM_IDLE flag has been added to the -mm tree. Its filename is zram-introduce-zram_idle-flag.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-introduce-zram_idle-flag.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-introduce-zram_idle-flag.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: introduce ZRAM_IDLE flag To support idle page writeback with upcoming patches, this patch introduces a new ZRAM_IDLE flag. Userspace can mark zram slots as "idle" via "echo all > /sys/block/zramX/idle" which marks every allocated zram slot as ZRAM_IDLE. User could see it by /sys/kernel/debug/zram/zram0/block_state. 300 75.033841 ...i 301 63.806904 s..i 302 63.806919 ..hi Once there is IO for the slot, the mark will be disappeared. 300 75.033841 ... 301 63.806904 s..i 302 63.806919 ..hi Therefore, 300th block is idle zpage. With this feature, user can how many zram has idle pages which are waste of memory. Link: http://lkml.kernel.org/r/20181127055429.251614-5-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Cc: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- Documentation/ABI/testing/sysfs-block-zram | 8 ++ Documentation/blockdev/zram.txt | 10 ++- drivers/block/zram/zram_drv.c | 57 ++++++++++++++++++- drivers/block/zram/zram_drv.h | 1 4 files changed, 69 insertions(+), 7 deletions(-) --- a/Documentation/ABI/testing/sysfs-block-zram~zram-introduce-zram_idle-flag +++ a/Documentation/ABI/testing/sysfs-block-zram @@ -98,3 +98,11 @@ Description: The backing_dev file is read-write and set up backing device for zram to write incompressible pages. For using, user should enable CONFIG_ZRAM_WRITEBACK. + +What: /sys/block/zram<id>/idle +Date: November 2018 +Contact: Minchan Kim <minchan(a)kernel.org> +Description: + idle file is write-only and mark zram slot as idle. + If system has mounted debugfs, user can see which slots + are idle via /sys/kernel/debug/zram/zram<id>/block_state --- a/Documentation/blockdev/zram.txt~zram-introduce-zram_idle-flag +++ a/Documentation/blockdev/zram.txt @@ -169,6 +169,7 @@ comp_algorithm RW show and change compact WO trigger memory compaction debug_stat RO this file is used for zram debugging purposes backing_dev RW set up backend storage for zram to write out +idle WO mark allocated slot as idle User space is advised to use the following files to read the device statistics. @@ -251,16 +252,17 @@ pages of the process with*pagemap. If you enable the feature, you could see block state via /sys/kernel/debug/zram/zram0/block_state". The output is as follows, - 300 75.033841 .wh - 301 63.806904 s.. - 302 63.806919 ..h + 300 75.033841 .wh. + 301 63.806904 s... + 302 63.806919 ..hi First column is zram's block index. Second column is access time since the system was booted Third column is state of the block. (s: same page w: written page to backing store -h: huge page) +h: huge page +i: idle page) First line of above example says 300th block is accessed at 75.033841sec and the block's state is huge so it is written back to the backing --- a/drivers/block/zram/zram_drv.c~zram-introduce-zram_idle-flag +++ a/drivers/block/zram/zram_drv.c @@ -281,6 +281,47 @@ static ssize_t mem_used_max_store(struct return len; } +static ssize_t idle_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; + int index; + char mode_buf[8]; + ssize_t sz; + + sz = strscpy(mode_buf, buf, sizeof(mode_buf)); + if (sz <= 0) + return -EINVAL; + + /* ignore trailing new line */ + if (mode_buf[sz - 1] == '\n') + mode_buf[sz - 1] = 0x00; + + if (strcmp(mode_buf, "all")) + return -EINVAL; + + down_read(&zram->init_lock); + if (!init_done(zram)) { + up_read(&zram->init_lock); + return -EINVAL; + } + + for (index = 0; index < nr_pages; index++) { + zram_slot_lock(zram, index); + if (!zram_allocated(zram, index)) + goto next; + + zram_set_flag(zram, index, ZRAM_IDLE); +next: + zram_slot_unlock(zram, index); + } + + up_read(&zram->init_lock); + + return len; +} + #ifdef CONFIG_ZRAM_WRITEBACK static void reset_bdev(struct zram *zram) { @@ -638,6 +679,7 @@ static void zram_debugfs_destroy(void) static void zram_accessed(struct zram *zram, u32 index) { + zram_clear_flag(zram, index, ZRAM_IDLE); zram->table[index].ac_time = ktime_get_boottime(); } @@ -670,12 +712,13 @@ static ssize_t read_block_state(struct f ts = ktime_to_timespec64(zram->table[index].ac_time); copied = snprintf(kbuf + written, count, - "%12zd %12lld.%06lu %c%c%c\n", + "%12zd %12lld.%06lu %c%c%c%c\n", index, (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC, zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.', zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.', - zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.'); + zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', + zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.'); if (count < copied) { zram_slot_unlock(zram, index); @@ -720,7 +763,10 @@ static void zram_debugfs_unregister(stru #else static void zram_debugfs_create(void) {}; static void zram_debugfs_destroy(void) {}; -static void zram_accessed(struct zram *zram, u32 index) {}; +static void zram_accessed(struct zram *zram, u32 index) +{ + zram_clear_flag(zram, index, ZRAM_IDLE); +}; static void zram_debugfs_register(struct zram *zram) {}; static void zram_debugfs_unregister(struct zram *zram) {}; #endif @@ -924,6 +970,9 @@ static void zram_free_page(struct zram * #ifdef CONFIG_ZRAM_MEMORY_TRACKING zram->table[index].ac_time = 0; #endif + if (zram_test_flag(zram, index, ZRAM_IDLE)) + zram_clear_flag(zram, index, ZRAM_IDLE); + if (zram_test_flag(zram, index, ZRAM_HUGE)) { zram_clear_flag(zram, index, ZRAM_HUGE); atomic64_dec(&zram->stats.huge_pages); @@ -1589,6 +1638,7 @@ static DEVICE_ATTR_RO(initstate); static DEVICE_ATTR_WO(reset); static DEVICE_ATTR_WO(mem_limit); static DEVICE_ATTR_WO(mem_used_max); +static DEVICE_ATTR_WO(idle); static DEVICE_ATTR_RW(max_comp_streams); static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK @@ -1602,6 +1652,7 @@ static struct attribute *zram_disk_attrs &dev_attr_compact.attr, &dev_attr_mem_limit.attr, &dev_attr_mem_used_max.attr, + &dev_attr_idle.attr, &dev_attr_max_comp_streams.attr, &dev_attr_comp_algorithm.attr, #ifdef CONFIG_ZRAM_WRITEBACK --- a/drivers/block/zram/zram_drv.h~zram-introduce-zram_idle-flag +++ a/drivers/block/zram/zram_drv.h @@ -48,6 +48,7 @@ enum zram_pageflags { ZRAM_SAME, /* Page consists the same element */ ZRAM_WB, /* page is stored on backing_device */ ZRAM_HUGE, /* Incompressible page */ + ZRAM_IDLE, /* not accessed page since last idle marking */ __NR_ZRAM_PAGEFLAGS, }; _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

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0
0 0

+ zram-refactoring-flags-and-writeback-stuff.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: refactor flags and writeback stuff has been added to the -mm tree. Its filename is zram-refactoring-flags-and-writeback-stuff.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-refactoring-flags-and-writeba… and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-refactoring-flags-and-writeba… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: refactor flags and writeback stuff Rename some variables and restructure some code for better readability in writeback and zs_free_page. Link: http://lkml.kernel.org/r/20181127055429.251614-4-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Cc: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- drivers/block/zram/zram_drv.c | 105 ++++++++++++-------------------- drivers/block/zram/zram_drv.h | 8 +- 2 files changed, 44 insertions(+), 69 deletions(-) --- a/drivers/block/zram/zram_drv.c~zram-refactoring-flags-and-writeback-stuff +++ a/drivers/block/zram/zram_drv.c @@ -55,17 +55,17 @@ static void zram_free_page(struct zram * static int zram_slot_trylock(struct zram *zram, u32 index) { - return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].value); + return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].flags); } static void zram_slot_lock(struct zram *zram, u32 index) { - bit_spin_lock(ZRAM_LOCK, &zram->table[index].value); + bit_spin_lock(ZRAM_LOCK, &zram->table[index].flags); } static void zram_slot_unlock(struct zram *zram, u32 index) { - bit_spin_unlock(ZRAM_LOCK, &zram->table[index].value); + bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags); } static inline bool init_done(struct zram *zram) @@ -76,7 +76,7 @@ static inline bool init_done(struct zram static inline bool zram_allocated(struct zram *zram, u32 index) { - return (zram->table[index].value >> (ZRAM_FLAG_SHIFT + 1)) || + return (zram->table[index].flags >> (ZRAM_FLAG_SHIFT + 1)) || zram->table[index].handle; } @@ -99,19 +99,19 @@ static void zram_set_handle(struct zram static bool zram_test_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { - return zram->table[index].value & BIT(flag); + return zram->table[index].flags & BIT(flag); } static void zram_set_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { - zram->table[index].value |= BIT(flag); + zram->table[index].flags |= BIT(flag); } static void zram_clear_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { - zram->table[index].value &= ~BIT(flag); + zram->table[index].flags &= ~BIT(flag); } static inline void zram_set_element(struct zram *zram, u32 index, @@ -127,15 +127,15 @@ static unsigned long zram_get_element(st static size_t zram_get_obj_size(struct zram *zram, u32 index) { - return zram->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1); + return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1); } static void zram_set_obj_size(struct zram *zram, u32 index, size_t size) { - unsigned long flags = zram->table[index].value >> ZRAM_FLAG_SHIFT; + unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT; - zram->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size; + zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size; } #if PAGE_SIZE != 4096 @@ -282,16 +282,11 @@ static ssize_t mem_used_max_store(struct } #ifdef CONFIG_ZRAM_WRITEBACK -static bool zram_wb_enabled(struct zram *zram) -{ - return zram->backing_dev; -} - static void reset_bdev(struct zram *zram) { struct block_device *bdev; - if (!zram_wb_enabled(zram)) + if (!zram->backing_dev) return; bdev = zram->bdev; @@ -318,7 +313,7 @@ static ssize_t backing_dev_show(struct d ssize_t ret; down_read(&zram->init_lock); - if (!zram_wb_enabled(zram)) { + if (!zram->backing_dev) { memcpy(buf, "none\n", 5); up_read(&zram->init_lock); return 5; @@ -447,7 +442,7 @@ out: return err; } -static unsigned long get_entry_bdev(struct zram *zram) +static unsigned long alloc_block_bdev(struct zram *zram) { unsigned long blk_idx = 1; retry: @@ -462,11 +457,11 @@ retry: return blk_idx; } -static void put_entry_bdev(struct zram *zram, unsigned long entry) +static void free_block_bdev(struct zram *zram, unsigned long blk_idx) { int was_set; - was_set = test_and_clear_bit(entry, zram->bitmap); + was_set = test_and_clear_bit(blk_idx, zram->bitmap); WARN_ON_ONCE(!was_set); } @@ -579,7 +574,7 @@ static int write_to_bdev(struct zram *zr if (!bio) return -ENOMEM; - entry = get_entry_bdev(zram); + entry = alloc_block_bdev(zram); if (!entry) { bio_put(bio); return -ENOSPC; @@ -590,7 +585,7 @@ static int write_to_bdev(struct zram *zr if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, bvec->bv_offset)) { bio_put(bio); - put_entry_bdev(zram, entry); + free_block_bdev(zram, entry); return -EIO; } @@ -608,18 +603,7 @@ static int write_to_bdev(struct zram *zr return 0; } -static void zram_wb_clear(struct zram *zram, u32 index) -{ - unsigned long entry; - - zram_clear_flag(zram, index, ZRAM_WB); - entry = zram_get_element(zram, index); - zram_set_element(zram, index, 0); - put_entry_bdev(zram, entry); -} - #else -static bool zram_wb_enabled(struct zram *zram) { return false; } static inline void reset_bdev(struct zram *zram) {}; static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, u32 index, struct bio *parent, @@ -634,7 +618,8 @@ static int read_from_bdev(struct zram *z { return -EIO; } -static void zram_wb_clear(struct zram *zram, u32 index) {} + +static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {}; #endif #ifdef CONFIG_ZRAM_MEMORY_TRACKING @@ -656,11 +641,6 @@ static void zram_accessed(struct zram *z zram->table[index].ac_time = ktime_get_boottime(); } -static void zram_reset_access(struct zram *zram, u32 index) -{ - zram->table[index].ac_time = 0; -} - static ssize_t read_block_state(struct file *file, char __user *buf, size_t count, loff_t *ppos) { @@ -741,7 +721,6 @@ static void zram_debugfs_unregister(stru static void zram_debugfs_create(void) {}; static void zram_debugfs_destroy(void) {}; static void zram_accessed(struct zram *zram, u32 index) {}; -static void zram_reset_access(struct zram *zram, u32 index) {}; static void zram_debugfs_register(struct zram *zram) {}; static void zram_debugfs_unregister(struct zram *zram) {}; #endif @@ -942,17 +921,18 @@ static void zram_free_page(struct zram * { unsigned long handle; - zram_reset_access(zram, index); - +#ifdef CONFIG_ZRAM_MEMORY_TRACKING + zram->table[index].ac_time = 0; +#endif if (zram_test_flag(zram, index, ZRAM_HUGE)) { zram_clear_flag(zram, index, ZRAM_HUGE); atomic64_dec(&zram->stats.huge_pages); } - if (zram_wb_enabled(zram) && zram_test_flag(zram, index, ZRAM_WB)) { - zram_wb_clear(zram, index); - atomic64_dec(&zram->stats.pages_stored); - return; + if (zram_test_flag(zram, index, ZRAM_WB)) { + zram_clear_flag(zram, index, ZRAM_WB); + free_block_bdev(zram, zram_get_element(zram, index)); + goto out; } /* @@ -961,10 +941,8 @@ static void zram_free_page(struct zram * */ if (zram_test_flag(zram, index, ZRAM_SAME)) { zram_clear_flag(zram, index, ZRAM_SAME); - zram_set_element(zram, index, 0); atomic64_dec(&zram->stats.same_pages); - atomic64_dec(&zram->stats.pages_stored); - return; + goto out; } handle = zram_get_handle(zram, index); @@ -975,10 +953,11 @@ static void zram_free_page(struct zram * atomic64_sub(zram_get_obj_size(zram, index), &zram->stats.compr_data_size); +out: atomic64_dec(&zram->stats.pages_stored); - zram_set_handle(zram, index, 0); zram_set_obj_size(zram, index, 0); + WARN_ON_ONCE(zram->table[index].flags & ~(1UL << ZRAM_LOCK)); } static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, @@ -989,24 +968,20 @@ static int __zram_bvec_read(struct zram unsigned int size; void *src, *dst; - if (zram_wb_enabled(zram)) { - zram_slot_lock(zram, index); - if (zram_test_flag(zram, index, ZRAM_WB)) { - struct bio_vec bvec; - - zram_slot_unlock(zram, index); + zram_slot_lock(zram, index); + if (zram_test_flag(zram, index, ZRAM_WB)) { + struct bio_vec bvec; - bvec.bv_page = page; - bvec.bv_len = PAGE_SIZE; - bvec.bv_offset = 0; - return read_from_bdev(zram, &bvec, - zram_get_element(zram, index), - bio, partial_io); - } zram_slot_unlock(zram, index); + + bvec.bv_page = page; + bvec.bv_len = PAGE_SIZE; + bvec.bv_offset = 0; + return read_from_bdev(zram, &bvec, + zram_get_element(zram, index), + bio, partial_io); } - zram_slot_lock(zram, index); handle = zram_get_handle(zram, index); if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) { unsigned long value; @@ -1118,7 +1093,7 @@ compress_again: if (unlikely(comp_len >= huge_class_size)) { comp_len = PAGE_SIZE; - if (zram_wb_enabled(zram) && allow_wb) { + if (zram->backing_dev && allow_wb) { zcomp_stream_put(zram->comp); ret = write_to_bdev(zram, bvec, index, bio, &element); if (!ret) { --- a/drivers/block/zram/zram_drv.h~zram-refactoring-flags-and-writeback-stuff +++ a/drivers/block/zram/zram_drv.h @@ -30,7 +30,7 @@ /* - * The lower ZRAM_FLAG_SHIFT bits of table.value is for + * The lower ZRAM_FLAG_SHIFT bits of table.flags is for * object size (excluding header), the higher bits is for * zram_pageflags. * @@ -41,7 +41,7 @@ */ #define ZRAM_FLAG_SHIFT 24 -/* Flags for zram pages (table[page_no].value) */ +/* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags { /* zram slot is locked */ ZRAM_LOCK = ZRAM_FLAG_SHIFT, @@ -60,7 +60,7 @@ struct zram_table_entry { unsigned long handle; unsigned long element; }; - unsigned long value; + unsigned long flags; #ifdef CONFIG_ZRAM_MEMORY_TRACKING ktime_t ac_time; #endif @@ -105,8 +105,8 @@ struct zram { * zram is claimed so open request will be failed */ bool claim; /* Protected by bdev->bd_mutex */ -#ifdef CONFIG_ZRAM_WRITEBACK struct file *backing_dev; +#ifdef CONFIG_ZRAM_WRITEBACK struct block_device *bdev; unsigned int old_block_size; unsigned long *bitmap; _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

1
0
0 0

+ zram-fix-double-free-backing-device.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: fix double free backing device has been added to the -mm tree. Its filename is zram-fix-double-free-backing-device.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-fix-double-free-backing-devic… and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-fix-double-free-backing-devic… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: fix double free backing device If blkdev_get fails, we shouldn't do blkdev_put. Otherwise, kernel emits below log. This patch fixes it. [ 31.073006] WARNING: CPU: 0 PID: 1893 at fs/block_dev.c:1828 blkdev_put+0x105/0x120 [ 31.075104] Modules linked in: [ 31.075898] CPU: 0 PID: 1893 Comm: swapoff Not tainted 4.19.0+ #453 [ 31.077484] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 31.079589] RIP: 0010:blkdev_put+0x105/0x120 [ 31.080606] Code: 48 c7 80 a0 00 00 00 00 00 00 00 48 c7 c7 40 e7 40 96 e8 6e 47 73 00 48 8b bb e0 00 00 00 e9 2c ff ff ff 0f 0b e9 75 ff ff ff <0f> 0b e9 5a ff ff ff 48 c7 80 a0 00 00 00 00 00 00 00 eb 87 0f 1f [ 31.085080] RSP: 0018:ffffb409005c7ed0 EFLAGS: 00010297 [ 31.086383] RAX: ffff9779fe5a8040 RBX: ffff9779fbc17300 RCX: 00000000b9fc37a4 [ 31.088105] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff9640e740 [ 31.089850] RBP: ffff9779fbc17318 R08: ffffffff95499a89 R09: 0000000000000004 [ 31.091201] R10: ffffb409005c7e50 R11: 7a9ef6088ff4d4a1 R12: 0000000000000083 [ 31.092276] R13: ffff9779fe607b98 R14: 0000000000000000 R15: ffff9779fe607a38 [ 31.093355] FS: 00007fc118d9b840(0000) GS:ffff9779fc600000(0000) knlGS:0000000000000000 [ 31.094582] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.095541] CR2: 00007fc11894b8dc CR3: 00000000339f6001 CR4: 0000000000160ef0 [ 31.096781] Call Trace: [ 31.097212] __x64_sys_swapoff+0x46d/0x490 [ 31.097914] do_syscall_64+0x5a/0x190 [ 31.098550] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.099402] RIP: 0033:0x7fc11843ec27 [ 31.100013] Code: 73 01 c3 48 8b 0d 71 62 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 41 62 2c 00 f7 d8 64 89 01 48 [ 31.103149] RSP: 002b:00007ffdf69be648 EFLAGS: 00000206 ORIG_RAX: 00000000000000a8 [ 31.104425] RAX: ffffffffffffffda RBX: 00000000011d98c0 RCX: 00007fc11843ec27 [ 31.105627] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 00000000011d98c0 [ 31.106847] RBP: 0000000000000001 R08: 00007ffdf69be690 R09: 0000000000000001 [ 31.108038] R10: 00000000000002b1 R11: 0000000000000206 R12: 0000000000000001 [ 31.109231] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 31.110433] irq event stamp: 4466 [ 31.111001] hardirqs last enabled at (4465): [<ffffffff953ebd43>] __free_pages_ok+0x1e3/0x490 [ 31.112437] hardirqs last disabled at (4466): [<ffffffff95201b7a>] trace_hardirqs_off_thunk+0x1a/0x1c [ 31.113973] softirqs last enabled at (3420): [<ffffffff95e00333>] __do_softirq+0x333/0x446 [ 31.115364] softirqs last disabled at (3407): [<ffffffff9527aee1>] irq_exit+0xd1/0xe0 Link: http://lkml.kernel.org/r/20181127055429.251614-3-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Cc: <stable(a)vger.kernel.org> [4.14+] Cc: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- drivers/block/zram/zram_drv.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/block/zram/zram_drv.c~zram-fix-double-free-backing-device +++ a/drivers/block/zram/zram_drv.c @@ -387,8 +387,10 @@ static ssize_t backing_dev_store(struct bdev = bdgrab(I_BDEV(inode)); err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram); - if (err < 0) + if (err < 0) { + bdev = NULL; goto out; + } nr_pages = i_size_read(inode) >> PAGE_SHIFT; bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long); _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

1
0
0 0

+ zram-fix-lockdep-warning-of-free-block-handling.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: fix lockdep warning of free block handling has been added to the -mm tree. Its filename is zram-fix-lockdep-warning-of-free-block-handling.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-fix-lockdep-warning-of-free-b… and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-fix-lockdep-warning-of-free-b… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan(a)kernel.org> Subject: zram: fix lockdep warning of free block handling Patch series "zram idle page writeback", v3. Inherently, swap device has many idle pages which are rare touched since it was allocated. It is never problem if we use storage device as swap. However, it's just waste for zram-swap. This patchset supports zram idle page writeback feature. * Admin can define what is idle page "no access since X time ago" * Admin can define when zram should writeback them * Admin can define when zram should stop writeback to prevent wearout Details are in each patch's description. This patch (of 7): [ 254.519728] ================================ [ 254.520311] WARNING: inconsistent lock state [ 254.520898] 4.19.0+ #390 Not tainted [ 254.521387] -------------------------------- [ 254.521732] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 254.521732] zram_verify/2095 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 254.521732] 00000000b1828693 (&(&zram->bitmap_lock)->rlock){+.?.}, at: put_entry_bdev+0x1e/0x50 [ 254.521732] {SOFTIRQ-ON-W} state was registered at: [ 254.521732] _raw_spin_lock+0x2c/0x40 [ 254.521732] zram_make_request+0x755/0xdc9 [ 254.521732] generic_make_request+0x373/0x6a0 [ 254.521732] submit_bio+0x6c/0x140 [ 254.521732] __swap_writepage+0x3a8/0x480 [ 254.521732] shrink_page_list+0x1102/0x1a60 [ 254.521732] shrink_inactive_list+0x21b/0x3f0 [ 254.521732] shrink_node_memcg.constprop.99+0x4f8/0x7e0 [ 254.521732] shrink_node+0x7d/0x2f0 [ 254.521732] do_try_to_free_pages+0xe0/0x300 [ 254.521732] try_to_free_pages+0x116/0x2b0 [ 254.521732] __alloc_pages_slowpath+0x3f4/0xf80 [ 254.521732] __alloc_pages_nodemask+0x2a2/0x2f0 [ 254.521732] __handle_mm_fault+0x42e/0xb50 [ 254.521732] handle_mm_fault+0x55/0xb0 [ 254.521732] __do_page_fault+0x235/0x4b0 [ 254.521732] page_fault+0x1e/0x30 [ 254.521732] irq event stamp: 228412 [ 254.521732] hardirqs last enabled at (228412): [<ffffffff98245846>] __slab_free+0x3e6/0x600 [ 254.521732] hardirqs last disabled at (228411): [<ffffffff98245625>] __slab_free+0x1c5/0x600 [ 254.521732] softirqs last enabled at (228396): [<ffffffff98e0031e>] __do_softirq+0x31e/0x427 [ 254.521732] softirqs last disabled at (228403): [<ffffffff98072051>] irq_exit+0xd1/0xe0 [ 254.521732] [ 254.521732] other info that might help us debug this: [ 254.521732] Possible unsafe locking scenario: [ 254.521732] [ 254.521732] CPU0 [ 254.521732] ---- [ 254.521732] lock(&(&zram->bitmap_lock)->rlock); [ 254.521732] <Interrupt> [ 254.521732] lock(&(&zram->bitmap_lock)->rlock); [ 254.521732] [ 254.521732] *** DEADLOCK *** [ 254.521732] [ 254.521732] no locks held by zram_verify/2095. [ 254.521732] [ 254.521732] stack backtrace: [ 254.521732] CPU: 5 PID: 2095 Comm: zram_verify Not tainted 4.19.0+ #390 [ 254.521732] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 254.521732] Call Trace: [ 254.521732] <IRQ> [ 254.521732] dump_stack+0x67/0x9b [ 254.521732] print_usage_bug+0x1bd/0x1d3 [ 254.521732] mark_lock+0x4aa/0x540 [ 254.521732] ? check_usage_backwards+0x160/0x160 [ 254.521732] __lock_acquire+0x51d/0x1300 [ 254.521732] ? free_debug_processing+0x24e/0x400 [ 254.521732] ? bio_endio+0x6d/0x1a0 [ 254.521732] ? lockdep_hardirqs_on+0x9b/0x180 [ 254.521732] ? lock_acquire+0x90/0x180 [ 254.521732] lock_acquire+0x90/0x180 [ 254.521732] ? put_entry_bdev+0x1e/0x50 [ 254.521732] _raw_spin_lock+0x2c/0x40 [ 254.521732] ? put_entry_bdev+0x1e/0x50 [ 254.521732] put_entry_bdev+0x1e/0x50 [ 254.521732] zram_free_page+0xf6/0x110 [ 254.521732] zram_slot_free_notify+0x42/0xa0 [ 254.521732] end_swap_bio_read+0x5b/0x170 [ 254.521732] blk_update_request+0x8f/0x340 [ 254.521732] scsi_end_request+0x2c/0x1e0 [ 254.521732] scsi_io_completion+0x98/0x650 [ 254.521732] blk_done_softirq+0x9e/0xd0 [ 254.521732] __do_softirq+0xcc/0x427 [ 254.521732] irq_exit+0xd1/0xe0 [ 254.521732] do_IRQ+0x93/0x120 [ 254.521732] common_interrupt+0xf/0xf [ 254.521732] </IRQ> With writeback feature, zram_slot_free_notify could be called in softirq context by end_swap_bio_read. However, bitmap_lock is not aware of that so lockdep yell out. Thanks. get_entry_bdev spin_lock(bitmap->lock); irq softirq end_swap_bio_read zram_slot_free_notify zram_slot_lock <-- deadlock prone zram_free_page put_entry_bdev spin_lock(bitmap->lock); <-- deadlock prone With akpm's suggestion (i.e. bitmap operation is already atomic), we could remove bitmap lock. It might fail to find a empty slot if serious contention happens. However, it's not severe problem because huge page writeback has already possiblity to fail if there is severe memory pressure. Worst case is just keeping the incompressible in memory, not storage. The other problem is zram_slot_lock in zram_slot_slot_free_notify. To make it safe is this patch introduces zram_slot_trylock where zram_slot_free_notify uses it. Although it's rare to be contented, this patch adds new debug stat "miss_free" to keep monitoring how often it happens. Link: http://lkml.kernel.org/r/20181127055429.251614-2-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Cc: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- drivers/block/zram/zram_drv.c | 38 +++++++++++++++++--------------- drivers/block/zram/zram_drv.h | 2 - 2 files changed, 22 insertions(+), 18 deletions(-) --- a/drivers/block/zram/zram_drv.c~zram-fix-lockdep-warning-of-free-block-handling +++ a/drivers/block/zram/zram_drv.c @@ -53,6 +53,11 @@ static size_t huge_class_size; static void zram_free_page(struct zram *zram, size_t index); +static int zram_slot_trylock(struct zram *zram, u32 index) +{ + return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].value); +} + static void zram_slot_lock(struct zram *zram, u32 index) { bit_spin_lock(ZRAM_LOCK, &zram->table[index].value); @@ -399,7 +404,6 @@ static ssize_t backing_dev_store(struct goto out; reset_bdev(zram); - spin_lock_init(&zram->bitmap_lock); zram->old_block_size = old_block_size; zram->bdev = bdev; @@ -443,29 +447,24 @@ out: static unsigned long get_entry_bdev(struct zram *zram) { - unsigned long entry; - - spin_lock(&zram->bitmap_lock); + unsigned long blk_idx = 1; +retry: /* skip 0 bit to confuse zram.handle = 0 */ - entry = find_next_zero_bit(zram->bitmap, zram->nr_pages, 1); - if (entry == zram->nr_pages) { - spin_unlock(&zram->bitmap_lock); + blk_idx = find_next_zero_bit(zram->bitmap, zram->nr_pages, blk_idx); + if (blk_idx == zram->nr_pages) return 0; - } - set_bit(entry, zram->bitmap); - spin_unlock(&zram->bitmap_lock); + if (test_and_set_bit(blk_idx, zram->bitmap)) + goto retry; - return entry; + return blk_idx; } static void put_entry_bdev(struct zram *zram, unsigned long entry) { int was_set; - spin_lock(&zram->bitmap_lock); was_set = test_and_clear_bit(entry, zram->bitmap); - spin_unlock(&zram->bitmap_lock); WARN_ON_ONCE(!was_set); } @@ -886,9 +885,10 @@ static ssize_t debug_stat_show(struct de down_read(&zram->init_lock); ret = scnprintf(buf, PAGE_SIZE, - "version: %d\n%8llu\n", + "version: %d\n%8llu %8llu\n", version, - (u64)atomic64_read(&zram->stats.writestall)); + (u64)atomic64_read(&zram->stats.writestall), + (u64)atomic64_read(&zram->stats.miss_free)); up_read(&zram->init_lock); return ret; @@ -1400,10 +1400,14 @@ static void zram_slot_free_notify(struct zram = bdev->bd_disk->private_data; - zram_slot_lock(zram, index); + atomic64_inc(&zram->stats.notify_free); + if (!zram_slot_trylock(zram, index)) { + atomic64_inc(&zram->stats.miss_free); + return; + } + zram_free_page(zram, index); zram_slot_unlock(zram, index); - atomic64_inc(&zram->stats.notify_free); } static int zram_rw_page(struct block_device *bdev, sector_t sector, --- a/drivers/block/zram/zram_drv.h~zram-fix-lockdep-warning-of-free-block-handling +++ a/drivers/block/zram/zram_drv.h @@ -79,6 +79,7 @@ struct zram_stats { atomic64_t pages_stored; /* no. of pages currently stored */ atomic_long_t max_used_pages; /* no. of maximum pages stored */ atomic64_t writestall; /* no. of write slow paths */ + atomic64_t miss_free; /* no. of missed free */ }; struct zram { @@ -110,7 +111,6 @@ struct zram { unsigned int old_block_size; unsigned long *bitmap; unsigned long nr_pages; - spinlock_t bitmap_lock; #endif #ifdef CONFIG_ZRAM_MEMORY_TRACKING struct dentry *debugfs_dir; _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-fix-lockdep-warning-of-free-block-handling.patch zram-fix-double-free-backing-device.patch zram-refactoring-flags-and-writeback-stuff.patch zram-introduce-zram_idle-flag.patch zram-support-idle-huge-page-writeback.patch zram-add-bd_stat-statistics.patch zram-writeback-throttle.patch

7 years

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[PATCH] Revert "drm/dp_mst: Skip validating ports during destruction, just ref"

by Lyude Paul

This reverts commit: c54c7374ff44 ("drm/dp_mst: Skip validating ports during destruction, just ref") ugh. In drm_dp_destroy_connector_work(), we have a pretty good chance of freeing the actual struct drm_dp_mst_port. However, after destroying things we send a hotplug through (*mgr->cbs->hotplug)(mgr) which is where the problems start. For i915, this calls all the way down to the fbcon probing helpers, which start trying to access the port in a modeset. [ 45.062001] ================================================================== [ 45.062112] BUG: KASAN: use-after-free in ex_handler_refcount+0x146/0x180 [ 45.062196] Write of size 4 at addr ffff8882b4b70968 by task kworker/3:1/53 [ 45.062325] CPU: 3 PID: 53 Comm: kworker/3:1 Kdump: loaded Tainted: G O 4.20.0-rc4Lyude-Test+ #3 [ 45.062442] Hardware name: LENOVO 20BWS1KY00/20BWS1KY00, BIOS JBET71WW (1.35 ) 09/14/2018 [ 45.062554] Workqueue: events drm_dp_destroy_connector_work [drm_kms_helper] [ 45.062641] Call Trace: [ 45.062685] dump_stack+0xbd/0x15a [ 45.062735] ? dump_stack_print_info.cold.0+0x1b/0x1b [ 45.062801] ? printk+0x9f/0xc5 [ 45.062847] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 45.062909] ? ex_handler_refcount+0x146/0x180 [ 45.062970] print_address_description+0x71/0x239 [ 45.063036] ? ex_handler_refcount+0x146/0x180 [ 45.063095] kasan_report.cold.5+0x242/0x30b [ 45.063155] __asan_report_store4_noabort+0x1c/0x20 [ 45.063313] ex_handler_refcount+0x146/0x180 [ 45.063371] ? ex_handler_clear_fs+0xb0/0xb0 [ 45.063428] fixup_exception+0x98/0xd7 [ 45.063484] ? raw_notifier_call_chain+0x20/0x20 [ 45.063548] do_trap+0x6d/0x210 [ 45.063605] ? _GLOBAL__sub_I_65535_1_drm_dp_aux_unregister_devnode+0x2f/0x1c6 [drm_kms_helper] [ 45.063732] do_error_trap+0xc0/0x170 [ 45.063802] ? _GLOBAL__sub_I_65535_1_drm_dp_aux_unregister_devnode+0x2f/0x1c6 [drm_kms_helper] [ 45.063929] do_invalid_op+0x3b/0x50 [ 45.063997] ? _GLOBAL__sub_I_65535_1_drm_dp_aux_unregister_devnode+0x2f/0x1c6 [drm_kms_helper] [ 45.064103] invalid_op+0x14/0x20 [ 45.064162] RIP: 0010:_GLOBAL__sub_I_65535_1_drm_dp_aux_unregister_devnode+0x2f/0x1c6 [drm_kms_helper] [ 45.064274] Code: 00 48 c7 c7 80 fe 53 a0 48 89 e5 e8 5b 6f 26 e1 5d c3 48 8d 0e 0f 0b 48 8d 0b 0f 0b 48 8d 0f 0f 0b 48 8d 0f 0f 0b 49 8d 4d 00 <0f> 0b 49 8d 0e 0f 0b 48 8d 08 0f 0b 49 8d 4d 00 0f 0b 48 8d 0b 0f [ 45.064569] RSP: 0018:ffff8882b789ee10 EFLAGS: 00010282 [ 45.064637] RAX: ffff8882af47ae70 RBX: ffff8882af47aa60 RCX: ffff8882b4b70968 [ 45.064723] RDX: ffff8882af47ae70 RSI: 0000000000000008 RDI: ffff8882b788bdb8 [ 45.064808] RBP: ffff8882b789ee28 R08: ffffed1056f13db4 R09: ffffed1056f13db3 [ 45.064894] R10: ffffed1056f13db3 R11: ffff8882b789ed9f R12: ffff8882af47ad28 [ 45.064980] R13: ffff8882b4b70968 R14: ffff8882acd86728 R15: ffff8882b4b75dc8 [ 45.065084] drm_dp_mst_reset_vcpi_slots+0x12/0x80 [drm_kms_helper] [ 45.065225] intel_mst_disable_dp+0xda/0x180 [i915] [ 45.065361] intel_encoders_disable.isra.107+0x197/0x310 [i915] [ 45.065498] haswell_crtc_disable+0xbe/0x400 [i915] [ 45.065622] ? i9xx_disable_plane+0x1c0/0x3e0 [i915] [ 45.065750] intel_atomic_commit_tail+0x74e/0x3e60 [i915] [ 45.065884] ? intel_pre_plane_update+0xbc0/0xbc0 [i915] [ 45.065968] ? drm_atomic_helper_swap_state+0x88b/0x1d90 [drm_kms_helper] [ 45.066054] ? kasan_check_write+0x14/0x20 [ 45.066165] ? i915_gem_track_fb+0x13a/0x330 [i915] [ 45.066277] ? i915_sw_fence_complete+0xe9/0x140 [i915] [ 45.066406] ? __i915_sw_fence_complete+0xc50/0xc50 [i915] [ 45.066540] intel_atomic_commit+0x72e/0xef0 [i915] [ 45.066635] ? drm_dev_dbg+0x200/0x200 [drm] [ 45.066764] ? intel_atomic_commit_tail+0x3e60/0x3e60 [i915] [ 45.066898] ? intel_atomic_commit_tail+0x3e60/0x3e60 [i915] [ 45.067001] drm_atomic_commit+0xc4/0xf0 [drm] [ 45.067074] restore_fbdev_mode_atomic+0x562/0x780 [drm_kms_helper] [ 45.067166] ? drm_fb_helper_debug_leave+0x690/0x690 [drm_kms_helper] [ 45.067249] ? kasan_check_read+0x11/0x20 [ 45.067324] restore_fbdev_mode+0x127/0x4b0 [drm_kms_helper] [ 45.067364] ? kasan_check_read+0x11/0x20 [ 45.067406] drm_fb_helper_restore_fbdev_mode_unlocked+0x164/0x200 [drm_kms_helper] [ 45.067462] ? drm_fb_helper_hotplug_event+0x30/0x30 [drm_kms_helper] [ 45.067508] ? kasan_check_write+0x14/0x20 [ 45.070360] ? mutex_unlock+0x22/0x40 [ 45.073748] drm_fb_helper_set_par+0xb2/0xf0 [drm_kms_helper] [ 45.075846] drm_fb_helper_hotplug_event.part.33+0x1cd/0x290 [drm_kms_helper] [ 45.078088] drm_fb_helper_hotplug_event+0x1c/0x30 [drm_kms_helper] [ 45.082614] intel_fbdev_output_poll_changed+0x9f/0x140 [i915] [ 45.087069] drm_kms_helper_hotplug_event+0x67/0x90 [drm_kms_helper] [ 45.089319] intel_dp_mst_hotplug+0x37/0x50 [i915] [ 45.091496] drm_dp_destroy_connector_work+0x510/0x6f0 [drm_kms_helper] [ 45.093675] ? drm_dp_update_payload_part1+0x1220/0x1220 [drm_kms_helper] [ 45.095851] ? kasan_check_write+0x14/0x20 [ 45.098473] ? kasan_check_read+0x11/0x20 [ 45.101155] ? strscpy+0x17c/0x530 [ 45.103808] ? __switch_to_asm+0x34/0x70 [ 45.106456] ? syscall_return_via_sysret+0xf/0x7f [ 45.109711] ? read_word_at_a_time+0x20/0x20 [ 45.113138] ? __switch_to_asm+0x40/0x70 [ 45.116529] ? __switch_to_asm+0x34/0x70 [ 45.119891] ? __switch_to_asm+0x40/0x70 [ 45.123224] ? __switch_to_asm+0x34/0x70 [ 45.126540] ? __switch_to_asm+0x34/0x70 [ 45.129824] process_one_work+0x88d/0x15d0 [ 45.133172] ? pool_mayday_timeout+0x850/0x850 [ 45.136459] ? pci_mmcfg_check_reserved+0x110/0x128 [ 45.139739] ? wake_q_add+0xb0/0xb0 [ 45.143010] ? check_preempt_wakeup+0x652/0x1050 [ 45.146304] ? worker_enter_idle+0x29e/0x740 [ 45.149589] ? __schedule+0x1ec0/0x1ec0 [ 45.152937] ? kasan_check_read+0x11/0x20 [ 45.156179] ? _raw_spin_lock_irq+0xa3/0x130 [ 45.159382] ? _raw_read_unlock_irqrestore+0x30/0x30 [ 45.162542] ? kasan_check_write+0x14/0x20 [ 45.165657] worker_thread+0x1a5/0x1470 [ 45.168725] ? set_load_weight+0x2e0/0x2e0 [ 45.171755] ? process_one_work+0x15d0/0x15d0 [ 45.174806] ? __switch_to_asm+0x34/0x70 [ 45.177645] ? __switch_to_asm+0x40/0x70 [ 45.180323] ? __switch_to_asm+0x34/0x70 [ 45.182936] ? __switch_to_asm+0x40/0x70 [ 45.185539] ? __switch_to_asm+0x34/0x70 [ 45.188100] ? __switch_to_asm+0x40/0x70 [ 45.190628] ? __schedule+0x7d4/0x1ec0 [ 45.193143] ? save_stack+0xa9/0xd0 [ 45.195632] ? kasan_check_write+0x10/0x20 [ 45.198162] ? kasan_kmalloc+0xc4/0xe0 [ 45.200609] ? kmem_cache_alloc_trace+0xdd/0x190 [ 45.203046] ? kthread+0x9f/0x3b0 [ 45.205470] ? ret_from_fork+0x35/0x40 [ 45.207876] ? unwind_next_frame+0x43/0x50 [ 45.210273] ? __save_stack_trace+0x82/0x100 [ 45.212658] ? deactivate_slab.isra.67+0x3d4/0x580 [ 45.215026] ? default_wake_function+0x35/0x50 [ 45.217399] ? kasan_check_read+0x11/0x20 [ 45.219825] ? _raw_spin_lock_irqsave+0xae/0x140 [ 45.222174] ? __lock_text_start+0x8/0x8 [ 45.224521] ? replenish_dl_entity.cold.62+0x4f/0x4f [ 45.226868] ? __kthread_parkme+0x87/0xf0 [ 45.229200] kthread+0x2f7/0x3b0 [ 45.231557] ? process_one_work+0x15d0/0x15d0 [ 45.233923] ? kthread_park+0x120/0x120 [ 45.236249] ret_from_fork+0x35/0x40 [ 45.240875] Allocated by task 242: [ 45.243136] save_stack+0x43/0xd0 [ 45.245385] kasan_kmalloc+0xc4/0xe0 [ 45.247597] kmem_cache_alloc_trace+0xdd/0x190 [ 45.249793] drm_dp_add_port+0x1e0/0x2170 [drm_kms_helper] [ 45.252000] drm_dp_send_link_address+0x4a7/0x740 [drm_kms_helper] [ 45.254389] drm_dp_check_and_send_link_address+0x1a7/0x210 [drm_kms_helper] [ 45.256803] drm_dp_mst_link_probe_work+0x6f/0xb0 [drm_kms_helper] [ 45.259200] process_one_work+0x88d/0x15d0 [ 45.261597] worker_thread+0x1a5/0x1470 [ 45.264038] kthread+0x2f7/0x3b0 [ 45.266371] ret_from_fork+0x35/0x40 [ 45.270937] Freed by task 53: [ 45.273170] save_stack+0x43/0xd0 [ 45.275382] __kasan_slab_free+0x139/0x190 [ 45.277604] kasan_slab_free+0xe/0x10 [ 45.279826] kfree+0x99/0x1b0 [ 45.282044] drm_dp_free_mst_port+0x4a/0x60 [drm_kms_helper] [ 45.284330] drm_dp_destroy_connector_work+0x43e/0x6f0 [drm_kms_helper] [ 45.286660] process_one_work+0x88d/0x15d0 [ 45.288934] worker_thread+0x1a5/0x1470 [ 45.291231] kthread+0x2f7/0x3b0 [ 45.293547] ret_from_fork+0x35/0x40 [ 45.298206] The buggy address belongs to the object at ffff8882b4b70968 which belongs to the cache kmalloc-2k of size 2048 [ 45.303047] The buggy address is located 0 bytes inside of 2048-byte region [ffff8882b4b70968, ffff8882b4b71168) [ 45.308010] The buggy address belongs to the page: [ 45.310477] page:ffffea000ad2dc00 count:1 mapcount:0 mapping:ffff8882c080cf40 index:0x0 compound_mapcount: 0 [ 45.313051] flags: 0x8000000000010200(slab|head) [ 45.315635] raw: 8000000000010200 ffffea000aac2808 ffffea000abe8608 ffff8882c080cf40 [ 45.318300] raw: 0000000000000000 00000000000d000d 00000001ffffffff 0000000000000000 [ 45.320966] page dumped because: kasan: bad access detected [ 45.326312] Memory state around the buggy address: [ 45.329085] ffff8882b4b70800: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 45.331845] ffff8882b4b70880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 45.334584] >ffff8882b4b70900: fc fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb [ 45.337302] ^ [ 45.340061] ffff8882b4b70980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.342910] ffff8882b4b70a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 45.345748] ================================================================== So, this definitely isn't a fix that we want. This being said; there's no real easy fix for this problem because of some of the catch-22's of the MST helpers current design. For starters; we always need to validate a port with drm_dp_get_validated_port_ref(), but validation relies on the lifetime of the port in the actual topology. So once the port is gone, it can't be validated again. If we were to try to make the payload helpers not use port validation, then we'd cause another problem: if the port isn't validated, it could be freed and we'd just start causing more KASAN issues. There are already hacks that attempt to workaround this in drm_dp_mst_destroy_connector_work() by re-initializing the kref so that it can be used again and it's memory can be freed once the VCPI helpers finish removing the port's respective payloads. But none of these really do anything helpful since the port still can't be validated since it's gone from the topology. Also, that workaround is immensely confusing to read through. What really needs to be done in order to fix this is to teach DRM how to track the lifetime of the structs for MST ports and branch devices seperately from their lifetime in the actual topology. Simply put; this means having two different krefs-one that removes the port/branch device from the topology, and one that finally calls kfree(). This would let us simplify things, since we'd now be able to keep ports around without having to keep them in the topology at the same time, which is exactly what we need in order to teach our VCPI helpers to only validate ports when it's actually necessary without running the risk of trying to use unallocated memory. Such a fix is on it's way, but for now let's play it safe and just revert this. If this bug has been around for well over a year, we can wait a little while to get an actual proper fix here. Signed-off-by: Lyude Paul <lyude(a)redhat.com> Fixes: c54c7374ff44 ("drm/dp_mst: Skip validating ports during destruction, just ref") Cc: Daniel Vetter <daniel(a)ffwll.ch> Cc: Sean Paul <sean(a)poorly.run> Cc: Jerry Zuo <Jerry.Zuo(a)amd.com> Cc: Harry Wentland <Harry.Wentland(a)amd.com> Cc: stable(a)vger.kernel.org # v4.6+ --- drivers/gpu/drm/drm_dp_mst_topology.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 08978ad72f33..529414556962 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1023,20 +1023,9 @@ static struct drm_dp_mst_port *drm_dp_mst_get_port_ref_locked(struct drm_dp_mst_ static struct drm_dp_mst_port *drm_dp_get_validated_port_ref(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port) { struct drm_dp_mst_port *rport = NULL; - mutex_lock(&mgr->lock); - /* - * Port may or may not be 'valid' but we don't care about that when - * destroying the port and we are guaranteed that the port pointer - * will be valid until we've finished - */ - if (current_work() == &mgr->destroy_connector_work) { - kref_get(&port->kref); - rport = port; - } else if (mgr->mst_primary) { - rport = drm_dp_mst_get_port_ref_locked(mgr->mst_primary, - port); - } + if (mgr->mst_primary) + rport = drm_dp_mst_get_port_ref_locked(mgr->mst_primary, port); mutex_unlock(&mgr->lock); return rport; } -- 2.19.2

7 years

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