August 2018 - Linux-stable-mirror

[patch 2/3] ipc/shm.c add ->pagesize function to shm_vm_ops

by akpm＠linux-foundation.org

From: Jane Chu <jane.chu(a)oracle.com> Subject: ipc/shm.c add ->pagesize function to shm_vm_ops 05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") adds a new ->pagesize() function to hugetlb_vm_ops, intended to cover all hugetlbfs backed files. With System V shared memory model, if "huge page" is specified, the "shared memory" is backed by hugetlbfs files, but the mappings initiated via shmget/shmat have their original vm_ops overwritten with shm_vm_ops, so we need to add a ->pagesize function to shm_vm_ops. Otherwise, vma_kernel_pagesize() returns PAGE_SIZE given a hugetlbfs backed vma, result in below BUG: fs/hugetlbfs/inode.c 443 if (unlikely(page_mapped(page))) { 444 BUG_ON(truncate_op); [ 242.268342] hugetlbfs: oracle (4592): Using mlock ulimits for SHM_HUGETLB is deprecated [ 282.653208] ------------[ cut here ]------------ [ 282.708447] kernel BUG at fs/hugetlbfs/inode.c:444! [ 282.818957] Modules linked in: nfsv3 rpcsec_gss_krb5 nfsv4 ... [ 284.025873] CPU: 35 PID: 5583 Comm: oracle_5583_sbt Not tainted 4.14.35-1829.el7uek.x86_64 #2 [ 284.246609] task: ffff9bf0507aaf80 task.stack: ffffa9e625628000 [ 284.317455] RIP: 0010:remove_inode_hugepages+0x3db/0x3e2 .... [ 285.292389] Call Trace: [ 285.321630] hugetlbfs_evict_inode+0x1e/0x3e [ 285.372707] evict+0xdb/0x1af [ 285.408185] iput+0x1a2/0x1f7 [ 285.443661] dentry_unlink_inode+0xc6/0xf0 [ 285.492661] __dentry_kill+0xd8/0x18d [ 285.536459] dput+0x1b5/0x1ed [ 285.571939] __fput+0x18b/0x216 [ 285.609495] ____fput+0xe/0x10 [ 285.646030] task_work_run+0x90/0xa7 [ 285.688788] exit_to_usermode_loop+0xdd/0x116 [ 285.740905] do_syscall_64+0x187/0x1ae [ 285.785740] entry_SYSCALL_64_after_hwframe+0x150/0x0 [jane.chu(a)oracle.com: relocate comment] Link: http://lkml.kernel.org/r/20180731044831.26036-1-jane.chu@oracle.com Link: http://lkml.kernel.org/r/20180727211727.5020-1-jane.chu@oracle.com Fixes: 05ea88608d4e13 ("mm, hugetlbfs: introduce ->pagesize() to vm_operations_struct") Signed-off-by: Jane Chu <jane.chu(a)oracle.com> Suggested-by: Mike Kravetz <mike.kravetz(a)oracle.com> Reviewed-by: Mike Kravetz <mike.kravetz(a)oracle.com> Acked-by: Davidlohr Bueso <dave(a)stgolabs.net> Acked-by: Michal Hocko <mhocko(a)suse.com> Cc: Dan Williams <dan.j.williams(a)intel.com> Cc: Jan Kara <jack(a)suse.cz> Cc: Jérôme Glisse <jglisse(a)redhat.com> Cc: Manfred Spraul <manfred(a)colorfullife.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- ipc/shm.c | 12 ++++++++++++ mm/hugetlb.c | 7 +++++++ 2 files changed, 19 insertions(+) --- a/ipc/shm.c~ipc-shmc-add-pagesize-function-to-shm_vm_ops +++ a/ipc/shm.c @@ -427,6 +427,17 @@ static int shm_split(struct vm_area_stru return 0; } +static unsigned long shm_pagesize(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + struct shm_file_data *sfd = shm_file_data(file); + + if (sfd->vm_ops->pagesize) + return sfd->vm_ops->pagesize(vma); + + return PAGE_SIZE; +} + #ifdef CONFIG_NUMA static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new) { @@ -554,6 +565,7 @@ static const struct vm_operations_struct .close = shm_close, /* callback for when the vm-area is released */ .fault = shm_fault, .split = shm_split, + .pagesize = shm_pagesize, #if defined(CONFIG_NUMA) .set_policy = shm_set_policy, .get_policy = shm_get_policy, --- a/mm/hugetlb.c~ipc-shmc-add-pagesize-function-to-shm_vm_ops +++ a/mm/hugetlb.c @@ -3167,6 +3167,13 @@ static vm_fault_t hugetlb_vm_op_fault(st return 0; } +/* + * When a new function is introduced to vm_operations_struct and added + * to hugetlb_vm_ops, please consider adding the function to shm_vm_ops. + * This is because under System V memory model, mappings created via + * shmget/shmat with "huge page" specified are backed by hugetlbfs files, + * their original vm_ops are overwritten with shm_vm_ops. + */ const struct vm_operations_struct hugetlb_vm_ops = { .fault = hugetlb_vm_op_fault, .open = hugetlb_vm_op_open, _

6 years, 4 months

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+ zram-remove-bd_cap_synchronous_io-with-writeback-feature.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: zram: remove BD_CAP_SYNCHRONOUS_IO with writeback feature has been added to the -mm tree. Its filename is zram-remove-bd_cap_synchronous_io-with-writeback-feature.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/zram-remove-bd_cap_synchronous_io-… and later at http://ozlabs.org/~akpm/mmotm/broken-out/zram-remove-bd_cap_synchronous_io-… 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: remove BD_CAP_SYNCHRONOUS_IO with writeback feature If zram supports writeback feature, it's no longer a BD_CAP_SYNCHRONOUS_IO device beause zram does synchronous IO operations for incompressible pages. Do not pretend to be synchronous IO device. It makes the system very sluggish due to waiting for IO completion from upper layers. Furthermore, it causes a user-after-free problem because swap thinks the opearion is done when the IO functions returns so it can free the page (e.g., lock_page_or_retry and goto out_release in do_swap_page) but in fact, IO is asynchrnous so the driver could access a just freed page afterward. This patch fixes the problem. BUG: Bad page state in process qemu-system-x86 pfn:3dfab21 page:ffffdfb137eac840 count:0 mapcount:0 mapping:0000000000000000 index:0x1 flags: 0x17fffc000000008(uptodate) raw: 017fffc000000008 dead000000000100 dead000000000200 0000000000000000 raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: PAGE_FLAGS_CHECK_AT_PREP flag set bad because of flags: 0x8(uptodate) Modules linked in: lz4 lz4_compress zram zsmalloc intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel bin fmt_misc pcbc aesni_intel aes_x86_64 crypto_simd cryptd iTCO_wdt glue_helper iTCO_vendor_support intel_cstate lpc_ich mei_me intel_uncore intel_rapl_perf pcspkr joydev sg mfd_core ioatdma mei wmi evdev ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter acpi_pad button ip_tables x_tables autofs4 ext4 crc32c_generic crc16 mbcache jbd2 fscrypto hid_generic usbhid hid sd_mod xhci_pci ehci_pci ahci libahci xhci_hcd ehci_hcd libata igb i2c_algo_bit crc32c_intel scsi_mod i2c_i8 01 dca usbcore CPU: 4 PID: 1039 Comm: qemu-system-x86 Tainted: G B 4.18.0-rc5+ #1 Hardware name: Supermicro Super Server/X10SRL-F, BIOS 2.0b 05/02/2017 Call Trace: dump_stack+0x5c/0x7b bad_page+0xba/0x120 get_page_from_freelist+0x1016/0x1250 __alloc_pages_nodemask+0xfa/0x250 alloc_pages_vma+0x7c/0x1c0 do_swap_page+0x347/0x920 ? __update_load_avg_se.isra.38+0x1eb/0x1f0 ? cpumask_next_wrap+0x3d/0x60 __handle_mm_fault+0x7b4/0x1110 ? update_load_avg+0x5ea/0x720 handle_mm_fault+0xfc/0x1f0 __get_user_pages+0x12f/0x690 get_user_pages_unlocked+0x148/0x1f0 __gfn_to_pfn_memslot+0xff/0x3c0 [kvm] try_async_pf+0x87/0x230 [kvm] tdp_page_fault+0x132/0x290 [kvm] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] kvm_mmu_page_fault+0x74/0x570 [kvm] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] ? vmexit_fill_RSB+0x18/0x30 [kvm_intel] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] ? vmx_vcpu_run+0x375/0x620 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x9b3/0x1990 [kvm] ? __update_load_avg_se.isra.38+0x1eb/0x1f0 ? kvm_vcpu_ioctl+0x388/0x5d0 [kvm] kvm_vcpu_ioctl+0x388/0x5d0 [kvm] ? __switch_to+0x395/0x450 ? __switch_to+0x395/0x450 do_vfs_ioctl+0xa2/0x630 ? __schedule+0x3fd/0x890 ksys_ioctl+0x70/0x80 ? exit_to_usermode_loop+0xca/0xf0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x55/0x100 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fb30361add7 Code: 00 00 00 48 8b 05 c1 80 2b 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 91 80 2b 00 f7 d8 64 89 01 48 RSP: 002b:00007fb2e97f98b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000000ae80 RCX: 00007fb30361add7 RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000015 RBP: 00005652b984e0f0 R08: 00005652b7d513d0 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb308c66000 R14: 0000000000000000 R15: 00005652b984e0f0 Link: https://lore.kernel.org/lkml/0516ae2d-b0fd-92c5-aa92-112ba7bd32fc@contabo.d… Link: http://lkml.kernel.org/r/20180802051112.86174-1-minchan@kernel.org Signed-off-by: Minchan Kim <minchan(a)kernel.org> Reported-by: Tino Lehnig <tino.lehnig(a)contabo.de> Tested-by: Tino Lehnig <tino.lehnig(a)contabo.de> Cc: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Cc: Jens Axboe <axboe(a)kernel.dk> Cc: <stable(a)vger.kernel.org> [4.15+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- drivers/block/zram/zram_drv.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/block/zram/zram_drv.c~zram-remove-bd_cap_synchronous_io-with-writeback-feature +++ a/drivers/block/zram/zram_drv.c @@ -298,7 +298,8 @@ static void reset_bdev(struct zram *zram zram->backing_dev = NULL; zram->old_block_size = 0; zram->bdev = NULL; - + zram->disk->queue->backing_dev_info->capabilities |= + BDI_CAP_SYNCHRONOUS_IO; kvfree(zram->bitmap); zram->bitmap = NULL; } @@ -400,6 +401,8 @@ static ssize_t backing_dev_store(struct zram->backing_dev = backing_dev; zram->bitmap = bitmap; zram->nr_pages = nr_pages; + zram->disk->queue->backing_dev_info->capabilities &= + ~BDI_CAP_SYNCHRONOUS_IO; up_write(&zram->init_lock); pr_info("setup backing device %s\n", file_name); _ Patches currently in -mm which might be from minchan(a)kernel.org are zram-remove-bd_cap_synchronous_io-with-writeback-feature.patch

6 years, 4 months

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[PATCH v4 2/8] drm/nouveau: Enable polling even if we have runtime PM

by Lyude Paul

Having runtime PM makes no difference on whether or not we want polling, and it's now safe to just enable polling unconditionally in drm_load() thanks to d61a5c106351 ("drm/nouveau: Fix deadlock on runtime suspend") Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Peter Ujfalusi <peter.ujfalusi(a)ti.com> Cc: stable(a)vger.kernel.org --- drivers/gpu/drm/nouveau/nouveau_drm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index 5fdc1fbe2ee5..ee2546db09c9 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -592,10 +592,11 @@ nouveau_drm_load(struct drm_device *dev, unsigned long flags) pm_runtime_allow(dev->dev); pm_runtime_mark_last_busy(dev->dev); pm_runtime_put(dev->dev); - } else { - /* enable polling for external displays */ - drm_kms_helper_poll_enable(dev); } + + /* enable polling for connectors without hpd */ + drm_kms_helper_poll_enable(dev); + return 0; fail_dispinit: -- 2.17.1

6 years, 4 months

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[PATCH v4 1/8] drm/nouveau: Fix bogus drm_kms_helper_poll_enable() placement

by Lyude Paul

Turns out this part is my fault for not noticing when reviewing 9a2eba337cace ("drm/nouveau: Fix drm poll_helper handling"). Currently we call drm_kms_helper_poll_enable() from nouveau_display_hpd_work(). This makes basically no sense however, because that means we're calling drm_kms_helper_poll_enable() every time we schedule the hotplug detection work. This is also against the advice mentioned in drm_kms_helper_poll_enable()'s documentation: Note that calls to enable and disable polling must be strictly ordered, which is automatically the case when they're only call from suspend/resume callbacks. Of course, hotplugs can't really be ordered. They could even happen immediately after we called drm_kms_helper_poll_disable() in nouveau_display_fini(), which can lead to all sorts of issues. Additionally; enabling polling /after/ we call drm_helper_hpd_irq_event() could also mean that we'd miss a hotplug event anyway, since drm_helper_hpd_irq_event() wouldn't bother trying to probe connectors so long as polling is disabled. So; simply move this back into nouveau_display_init() again. The race condition that both of these patches attempted to work around has already been fixed properly in d61a5c106351 ("drm/nouveau: Fix deadlock on runtime suspend") Fixes: 9a2eba337cace ("drm/nouveau: Fix drm poll_helper handling") Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Peter Ujfalusi <peter.ujfalusi(a)ti.com> Cc: stable(a)vger.kernel.org --- drivers/gpu/drm/nouveau/nouveau_display.c | 7 +++++-- drivers/gpu/drm/nouveau/nouveau_drm.c | 1 - 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c index ec7861457b84..1d36ab5d4796 100644 --- a/drivers/gpu/drm/nouveau/nouveau_display.c +++ b/drivers/gpu/drm/nouveau/nouveau_display.c @@ -355,8 +355,6 @@ nouveau_display_hpd_work(struct work_struct *work) pm_runtime_get_sync(drm->dev->dev); drm_helper_hpd_irq_event(drm->dev); - /* enable polling for external displays */ - drm_kms_helper_poll_enable(drm->dev); pm_runtime_mark_last_busy(drm->dev->dev); pm_runtime_put_sync(drm->dev->dev); @@ -411,6 +409,11 @@ nouveau_display_init(struct drm_device *dev) if (ret) return ret; + /* enable connector detection and polling for connectors without HPD + * support + */ + drm_kms_helper_poll_enable(dev); + /* enable hotplug interrupts */ drm_connector_list_iter_begin(dev, &conn_iter); nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) { diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index c7ec86d6c3c9..5fdc1fbe2ee5 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -835,7 +835,6 @@ nouveau_pmops_runtime_suspend(struct device *dev) return -EBUSY; } - drm_kms_helper_poll_disable(drm_dev); nouveau_switcheroo_optimus_dsm(); ret = nouveau_do_suspend(drm_dev, true); pci_save_state(pdev); -- 2.17.1

6 years, 4 months

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[PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock

by Bart Van Assche

A long time ago the unfortunate decision was taken to add a self- deletion attribute to the sysfs SCSI device directory. That decision was unfortunate because self-deletion is really tricky. We can't drop that attribute because widely used user space software depends on it, namely the rescan-scsi-bus.sh script. Hence this patch that avoids that writing into that attribute triggers a deadlock. See also commit 7973cbd9fbd9 ("[PATCH] add sysfs attributes to scan and delete scsi_devices"). This patch avoids that self-removal triggers the following deadlock: ====================================================== WARNING: possible circular locking dependency detected 4.18.0-rc2-dbg+ #5 Not tainted ------------------------------------------------------ modprobe/6539 is trying to acquire lock: 000000008323c4cd (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x45/0x90 but task is already holding lock: 00000000a6ec2c69 (&shost->scan_mutex){+.+.}, at: scsi_remove_host+0x21/0x150 [scsi_mod] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&shost->scan_mutex){+.+.}: __mutex_lock+0xfe/0xc70 mutex_lock_nested+0x1b/0x20 scsi_remove_device+0x26/0x40 [scsi_mod] sdev_store_delete+0x27/0x30 [scsi_mod] dev_attr_store+0x3e/0x50 sysfs_kf_write+0x87/0xa0 kernfs_fop_write+0x190/0x230 __vfs_write+0xd2/0x3b0 vfs_write+0x101/0x270 ksys_write+0xab/0x120 __x64_sys_write+0x43/0x50 do_syscall_64+0x77/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (kn->count#202){++++}: lock_acquire+0xd2/0x260 __kernfs_remove+0x424/0x4a0 kernfs_remove_by_name_ns+0x45/0x90 remove_files.isra.1+0x3a/0x90 sysfs_remove_group+0x5c/0xc0 sysfs_remove_groups+0x39/0x60 device_remove_attrs+0x82/0xb0 device_del+0x251/0x580 __scsi_remove_device+0x19f/0x1d0 [scsi_mod] scsi_forget_host+0x37/0xb0 [scsi_mod] scsi_remove_host+0x9b/0x150 [scsi_mod] sdebug_driver_remove+0x4b/0x150 [scsi_debug] device_release_driver_internal+0x241/0x360 device_release_driver+0x12/0x20 bus_remove_device+0x1bc/0x290 device_del+0x259/0x580 device_unregister+0x1a/0x70 sdebug_remove_adapter+0x8b/0xf0 [scsi_debug] scsi_debug_exit+0x76/0xe8 [scsi_debug] __x64_sys_delete_module+0x1c1/0x280 do_syscall_64+0x77/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&shost->scan_mutex); lock(kn->count#202); lock(&shost->scan_mutex); lock(kn->count#202); *** DEADLOCK *** 2 locks held by modprobe/6539: #0: 00000000efaf9298 (&dev->mutex){....}, at: device_release_driver_internal+0x68/0x360 #1: 00000000a6ec2c69 (&shost->scan_mutex){+.+.}, at: scsi_remove_host+0x21/0x150 [scsi_mod] stack backtrace: CPU: 10 PID: 6539 Comm: modprobe Not tainted 4.18.0-rc2-dbg+ #5 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 Call Trace: dump_stack+0xa4/0xf5 print_circular_bug.isra.34+0x213/0x221 __lock_acquire+0x1a7e/0x1b50 lock_acquire+0xd2/0x260 __kernfs_remove+0x424/0x4a0 kernfs_remove_by_name_ns+0x45/0x90 remove_files.isra.1+0x3a/0x90 sysfs_remove_group+0x5c/0xc0 sysfs_remove_groups+0x39/0x60 device_remove_attrs+0x82/0xb0 device_del+0x251/0x580 __scsi_remove_device+0x19f/0x1d0 [scsi_mod] scsi_forget_host+0x37/0xb0 [scsi_mod] scsi_remove_host+0x9b/0x150 [scsi_mod] sdebug_driver_remove+0x4b/0x150 [scsi_debug] device_release_driver_internal+0x241/0x360 device_release_driver+0x12/0x20 bus_remove_device+0x1bc/0x290 device_del+0x259/0x580 device_unregister+0x1a/0x70 sdebug_remove_adapter+0x8b/0xf0 [scsi_debug] scsi_debug_exit+0x76/0xe8 [scsi_debug] __x64_sys_delete_module+0x1c1/0x280 do_syscall_64+0x77/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xbe See also https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg54525.html. Fixes: ac0ece9174ac ("scsi: use device_remove_file_self() instead of device_schedule_callback()") Signed-off-by: Bart Van Assche <bart.vanassche(a)wdc.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Acked-by: Tejun Heo <tj(a)kernel.org> Cc: Johannes Thumshirn <jthumshirn(a)suse.de> Cc: <stable(a)vger.kernel.org> --- drivers/scsi/scsi_sysfs.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index de122354d09a..3aee9464a7bf 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -722,8 +722,24 @@ static ssize_t sdev_store_delete(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { - if (device_remove_file_self(dev, attr)) - scsi_remove_device(to_scsi_device(dev)); + struct kernfs_node *kn; + + kn = sysfs_break_active_protection(&dev->kobj, &attr->attr); + WARN_ON_ONCE(!kn); + /* + * Concurrent writes into the "delete" sysfs attribute may trigger + * concurrent calls to device_remove_file() and scsi_remove_device(). + * device_remove_file() handles concurrent removal calls by + * serializing these and by ignoring the second and later removal + * attempts. Concurrent calls of scsi_remove_device() are + * serialized. The second and later calls of scsi_remove_device() are + * ignored because the first call of that function changes the device + * state into SDEV_DEL. + */ + device_remove_file(dev, attr); + scsi_remove_device(to_scsi_device(dev)); + if (kn) + sysfs_unbreak_active_protection(kn); return count; }; static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete); -- 2.18.0

6 years, 4 months

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[PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection()

by Bart Van Assche

Introduce these two functions and export them such that the next patch can add calls to these functions from the SCSI core. Signed-off-by: Bart Van Assche <bart.vanassche(a)wdc.com> Acked-by: Tejun Heo <tj(a)kernel.org> Acked-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: <stable(a)vger.kernel.org> --- fs/sysfs/file.c | 44 +++++++++++++++++++++++++++++++++++++++++++ include/linux/sysfs.h | 14 ++++++++++++++ 2 files changed, 58 insertions(+) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 5c13f29bfcdb..118fa197a35f 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -405,6 +405,50 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr, } EXPORT_SYMBOL_GPL(sysfs_chmod_file); +/** + * sysfs_break_active_protection - break "active" protection + * @kobj: The kernel object @attr is associated with. + * @attr: The attribute to break the "active" protection for. + * + * With sysfs, just like kernfs, deletion of an attribute is postponed until + * all active .show() and .store() callbacks have finished unless this function + * is called. Hence this function is useful in methods that implement self + * deletion. + */ +struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj, + const struct attribute *attr) +{ + struct kernfs_node *kn; + + kobject_get(kobj); + kn = kernfs_find_and_get(kobj->sd, attr->name); + if (kn) + kernfs_break_active_protection(kn); + return kn; +} +EXPORT_SYMBOL_GPL(sysfs_break_active_protection); + +/** + * sysfs_unbreak_active_protection - restore "active" protection + * @kn: Pointer returned by sysfs_break_active_protection(). + * + * Undo the effects of sysfs_break_active_protection(). Since this function + * calls kernfs_put() on the kernfs node that corresponds to the 'attr' + * argument passed to sysfs_break_active_protection() that attribute may have + * been removed between the sysfs_break_active_protection() and + * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after + * this function has returned. + */ +void sysfs_unbreak_active_protection(struct kernfs_node *kn) +{ + struct kobject *kobj = kn->parent->priv; + + kernfs_unbreak_active_protection(kn); + kernfs_put(kn); + kobject_put(kobj); +} +EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection); + /** * sysfs_remove_file_ns - remove an object attribute with a custom ns tag * @kobj: object we're acting for diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index b8bfdc173ec0..3c12198c0103 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -237,6 +237,9 @@ int __must_check sysfs_create_files(struct kobject *kobj, const struct attribute **attr); int __must_check sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr, umode_t mode); +struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj, + const struct attribute *attr); +void sysfs_unbreak_active_protection(struct kernfs_node *kn); void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr, const void *ns); bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr); @@ -350,6 +353,17 @@ static inline int sysfs_chmod_file(struct kobject *kobj, return 0; } +static inline struct kernfs_node * +sysfs_break_active_protection(struct kobject *kobj, + const struct attribute *attr) +{ + return NULL; +} + +static inline void sysfs_unbreak_active_protection(struct kernfs_node *kn) +{ +} + static inline void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr, const void *ns) -- 2.18.0

6 years, 4 months

1
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0 0

[PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock

by Bart Van Assche

A long time ago the unfortunate decision was taken to add a self- deletion attribute to the sysfs SCSI device directory. That decision was unfortunate because self-deletion is really tricky. We can't drop that attribute because widely used user space software depends on it, namely the rescan-scsi-bus.sh script. Hence this patch that avoids that writing into that attribute triggers a deadlock. See also commit 7973cbd9fbd9 ("[PATCH] add sysfs attributes to scan and delete scsi_devices"). This patch avoids that self-removal triggers the following deadlock: ====================================================== WARNING: possible circular locking dependency detected 4.18.0-rc2-dbg+ #5 Not tainted ------------------------------------------------------ modprobe/6539 is trying to acquire lock: 000000008323c4cd (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x45/0x90 but task is already holding lock: 00000000a6ec2c69 (&shost->scan_mutex){+.+.}, at: scsi_remove_host+0x21/0x150 [scsi_mod] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&shost->scan_mutex){+.+.}: __mutex_lock+0xfe/0xc70 mutex_lock_nested+0x1b/0x20 scsi_remove_device+0x26/0x40 [scsi_mod] sdev_store_delete+0x27/0x30 [scsi_mod] dev_attr_store+0x3e/0x50 sysfs_kf_write+0x87/0xa0 kernfs_fop_write+0x190/0x230 __vfs_write+0xd2/0x3b0 vfs_write+0x101/0x270 ksys_write+0xab/0x120 __x64_sys_write+0x43/0x50 do_syscall_64+0x77/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (kn->count#202){++++}: lock_acquire+0xd2/0x260 __kernfs_remove+0x424/0x4a0 kernfs_remove_by_name_ns+0x45/0x90 remove_files.isra.1+0x3a/0x90 sysfs_remove_group+0x5c/0xc0 sysfs_remove_groups+0x39/0x60 device_remove_attrs+0x82/0xb0 device_del+0x251/0x580 __scsi_remove_device+0x19f/0x1d0 [scsi_mod] scsi_forget_host+0x37/0xb0 [scsi_mod] scsi_remove_host+0x9b/0x150 [scsi_mod] sdebug_driver_remove+0x4b/0x150 [scsi_debug] device_release_driver_internal+0x241/0x360 device_release_driver+0x12/0x20 bus_remove_device+0x1bc/0x290 device_del+0x259/0x580 device_unregister+0x1a/0x70 sdebug_remove_adapter+0x8b/0xf0 [scsi_debug] scsi_debug_exit+0x76/0xe8 [scsi_debug] __x64_sys_delete_module+0x1c1/0x280 do_syscall_64+0x77/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&shost->scan_mutex); lock(kn->count#202); lock(&shost->scan_mutex); lock(kn->count#202); *** DEADLOCK *** 2 locks held by modprobe/6539: #0: 00000000efaf9298 (&dev->mutex){....}, at: device_release_driver_internal+0x68/0x360 #1: 00000000a6ec2c69 (&shost->scan_mutex){+.+.}, at: scsi_remove_host+0x21/0x150 [scsi_mod] stack backtrace: CPU: 10 PID: 6539 Comm: modprobe Not tainted 4.18.0-rc2-dbg+ #5 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 Call Trace: dump_stack+0xa4/0xf5 print_circular_bug.isra.34+0x213/0x221 __lock_acquire+0x1a7e/0x1b50 lock_acquire+0xd2/0x260 __kernfs_remove+0x424/0x4a0 kernfs_remove_by_name_ns+0x45/0x90 remove_files.isra.1+0x3a/0x90 sysfs_remove_group+0x5c/0xc0 sysfs_remove_groups+0x39/0x60 device_remove_attrs+0x82/0xb0 device_del+0x251/0x580 __scsi_remove_device+0x19f/0x1d0 [scsi_mod] scsi_forget_host+0x37/0xb0 [scsi_mod] scsi_remove_host+0x9b/0x150 [scsi_mod] sdebug_driver_remove+0x4b/0x150 [scsi_debug] device_release_driver_internal+0x241/0x360 device_release_driver+0x12/0x20 bus_remove_device+0x1bc/0x290 device_del+0x259/0x580 device_unregister+0x1a/0x70 sdebug_remove_adapter+0x8b/0xf0 [scsi_debug] scsi_debug_exit+0x76/0xe8 [scsi_debug] __x64_sys_delete_module+0x1c1/0x280 do_syscall_64+0x77/0x230 entry_SYSCALL_64_after_hwframe+0x49/0xbe See also https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg54525.html. Fixes: ac0ece9174ac ("scsi: use device_remove_file_self() instead of device_schedule_callback()") Signed-off-by: Bart Van Assche <bart.vanassche(a)wdc.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: Tejun Heo <tj(a)kernel.org> Cc: Johannes Thumshirn <jthumshirn(a)suse.de> Cc: <stable(a)vger.kernel.org> --- drivers/scsi/scsi_sysfs.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index de122354d09a..3aee9464a7bf 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -722,8 +722,24 @@ static ssize_t sdev_store_delete(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { - if (device_remove_file_self(dev, attr)) - scsi_remove_device(to_scsi_device(dev)); + struct kernfs_node *kn; + + kn = sysfs_break_active_protection(&dev->kobj, &attr->attr); + WARN_ON_ONCE(!kn); + /* + * Concurrent writes into the "delete" sysfs attribute may trigger + * concurrent calls to device_remove_file() and scsi_remove_device(). + * device_remove_file() handles concurrent removal calls by + * serializing these and by ignoring the second and later removal + * attempts. Concurrent calls of scsi_remove_device() are + * serialized. The second and later calls of scsi_remove_device() are + * ignored because the first call of that function changes the device + * state into SDEV_DEL. + */ + device_remove_file(dev, attr); + scsi_remove_device(to_scsi_device(dev)); + if (kn) + sysfs_unbreak_active_protection(kn); return count; }; static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete); -- 2.18.0

6 years, 4 months

3
4
0 0

[PATCH] block: really disable runtime-pm for blk-mq

by Ming Lei

Runtime PM isn't ready for blk-mq yet, and commit 765e40b675a9 ("block: disable runtime-pm for blk-mq") tried to disable it. Unfortunately, it can't take effect in that way since user space still can switch it on via 'echo auto > /sys/block/sdN/device/power/control'. This patch disables runtime-pm for blk-mq really by pm_runtime_disable() and fixes all kinds of PM related kernel crash. Cc: Christoph Hellwig <hch(a)lst.de> Cc: Patrick Steinhardt <ps(a)pks.im> Cc: Bart Van Assche <Bart.VanAssche(a)wdc.com> Cc: Tomas Janousek <tomi(a)nomi.cz> Cc: Przemek Socha <soprwa(a)gmail.com> Cc: Alan Stern <stern(a)rowland.harvard.edu> Cc: <stable(a)vger.kernel.org> Signed-off-by: Ming Lei <ming.lei(a)redhat.com> --- block/blk-core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 03a4ea93a5f3..090b782df129 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -3769,9 +3769,11 @@ EXPORT_SYMBOL(blk_finish_plug); */ void blk_pm_runtime_init(struct request_queue *q, struct device *dev) { - /* not support for RQF_PM and ->rpm_status in blk-mq yet */ - if (q->mq_ops) + /* Don't enable runtime PM for blk-mq until it is ready */ + if (q->mq_ops) { + pm_runtime_disable(dev); return; + } q->dev = dev; q->rpm_status = RPM_ACTIVE; -- 2.9.5

6 years, 4 months

6
5
0 0

[PATCH v4.14] iwlwifi: pcie: don't warn if we use all the transmit pointers

by Emmanuel Grumbach

commit 4437ba7ee7de7e71d11deb91c87a370e4ffd2601 upstream. Our Transmit Frame Descriptor (TFD) is a DMA descriptor that includes several pointers to be able to transmit a packet which is not physically contiguous. Depending on the hardware being use, we can have 20 or 25 pointers in a single TFD. In both cases, it is more than enough and it is quite hard to hit this limit. It has been reported that when using specific applications (Ktorrent), we can actually use all the pointers and then a long standing bug showed up. When we free the TFD, we check its number of valid pointers and make sure it doesn't exceed the number of pointers the hardware support. This check had an off by one bug: it is perfectly valid to free the 20 pointers if the TFD has 20 pointers. Fix that. https://bugzilla.kernel.org/show_bug.cgi?id=197981 Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach(a)intel.com> Signed-off-by: Luca Coelho <luciano.coelho(a)intel.com> --- drivers/net/wireless/intel/iwlwifi/pcie/tx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c index 4704137..4c3b134 100644 --- a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c +++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c @@ -378,7 +378,7 @@ static void iwl_pcie_tfd_unmap(struct iwl_trans *trans, /* Sanity check on number of chunks */ num_tbs = iwl_pcie_tfd_get_num_tbs(trans, tfd); - if (num_tbs >= trans_pcie->max_tbs) { + if (num_tbs > trans_pcie->max_tbs) { IWL_ERR(trans, "Too many chunks: %i\n", num_tbs); /* @todo issue fatal error, it is quite serious situation */ return; -- 2.7.4

6 years, 4 months

1
0
0 0

[PATCH v4.9] iwlwifi: pcie: don't warn if we use all the transmit pointers

by Emmanuel Grumbach

commit 4437ba7ee7de7e71d11deb91c87a370e4ffd2601 upstream. Our Transmit Frame Descriptor (TFD) is a DMA descriptor that includes several pointers to be able to transmit a packet which is not physically contiguous. Depending on the hardware being use, we can have 20 or 25 pointers in a single TFD. In both cases, it is more than enough and it is quite hard to hit this limit. It has been reported that when using specific applications (Ktorrent), we can actually use all the pointers and then a long standing bug showed up. When we free the TFD, we check its number of valid pointers and make sure it doesn't exceed the number of pointers the hardware support. This check had an off by one bug: it is perfectly valid to free the 20 pointers if the TFD has 20 pointers. Fix that. https://bugzilla.kernel.org/show_bug.cgi?id=197981 Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach(a)intel.com> Signed-off-by: Luca Coelho <luciano.coelho(a)intel.com> --- drivers/net/wireless/intel/iwlwifi/pcie/tx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c index e1bfc95..2c98784 100644 --- a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c +++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c @@ -416,7 +416,7 @@ static void iwl_pcie_tfd_unmap(struct iwl_trans *trans, /* Sanity check on number of chunks */ num_tbs = iwl_pcie_tfd_get_num_tbs(trans, tfd); - if (num_tbs >= trans_pcie->max_tbs) { + if (num_tbs > trans_pcie->max_tbs) { IWL_ERR(trans, "Too many chunks: %i\n", num_tbs); /* @todo issue fatal error, it is quite serious situation */ return; -- 2.7.4

6 years, 4 months

1
0
0 0

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Linux-stable-mirror August 2018