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[patch 135/167] hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined

by akpm＠linux-foundation.org

From: Michal Hocko <mhocko(a)suse.com> Subject: hwpoison, memory_hotplug: allow hwpoisoned pages to be offlined We have received a bug report that an injected MCE about faulty memory prevents memory offline to succeed on 4.4 base kernel. The underlying reason was that the HWPoison page has an elevated reference count and the migration keeps failing. There are two problems with that. First of all it is dubious to migrate the poisoned page because we know that accessing that memory is possible to fail. Secondly it doesn't make any sense to migrate a potentially broken content and preserve the memory corruption over to a new location. Oscar has found out that 4.4 and the current upstream kernels behave slightly differently with his simply testcase === int main(void) { int ret; int i; int fd; char *array = malloc(4096); char *array_locked = malloc(4096); fd = open("/tmp/data", O_RDONLY); read(fd, array, 4095); for (i = 0; i < 4096; i++) array_locked[i] = 'd'; ret = mlock((void *)PAGE_ALIGN((unsigned long)array_locked), sizeof(array_locked)); if (ret) perror("mlock"); sleep (20); ret = madvise((void *)PAGE_ALIGN((unsigned long)array_locked), 4096, MADV_HWPOISON); if (ret) perror("madvise"); for (i = 0; i < 4096; i++) array_locked[i] = 'd'; return 0; } === + offline this memory. In 4.4 kernels he saw the hwpoisoned page to be returned back to the LRU list kernel: [<ffffffff81019ac9>] dump_trace+0x59/0x340 kernel: [<ffffffff81019e9a>] show_stack_log_lvl+0xea/0x170 kernel: [<ffffffff8101ac71>] show_stack+0x21/0x40 kernel: [<ffffffff8132bb90>] dump_stack+0x5c/0x7c kernel: [<ffffffff810815a1>] warn_slowpath_common+0x81/0xb0 kernel: [<ffffffff811a275c>] __pagevec_lru_add_fn+0x14c/0x160 kernel: [<ffffffff811a2eed>] pagevec_lru_move_fn+0xad/0x100 kernel: [<ffffffff811a334c>] __lru_cache_add+0x6c/0xb0 kernel: [<ffffffff81195236>] add_to_page_cache_lru+0x46/0x70 kernel: [<ffffffffa02b4373>] extent_readpages+0xc3/0x1a0 [btrfs] kernel: [<ffffffff811a16d7>] __do_page_cache_readahead+0x177/0x200 kernel: [<ffffffff811a18c8>] ondemand_readahead+0x168/0x2a0 kernel: [<ffffffff8119673f>] generic_file_read_iter+0x41f/0x660 kernel: [<ffffffff8120e50d>] __vfs_read+0xcd/0x140 kernel: [<ffffffff8120e9ea>] vfs_read+0x7a/0x120 kernel: [<ffffffff8121404b>] kernel_read+0x3b/0x50 kernel: [<ffffffff81215c80>] do_execveat_common.isra.29+0x490/0x6f0 kernel: [<ffffffff81215f08>] do_execve+0x28/0x30 kernel: [<ffffffff81095ddb>] call_usermodehelper_exec_async+0xfb/0x130 kernel: [<ffffffff8161c045>] ret_from_fork+0x55/0x80 And that latter confuses the hotremove path because an LRU page is attempted to be migrated and that fails due to an elevated reference count. It is quite possible that the reuse of the HWPoisoned page is some kind of fixed race condition but I am not really sure about that. With the upstream kernel the failure is slightly different. The page doesn't seem to have LRU bit set but isolate_movable_page simply fails and do_migrate_range simply puts all the isolated pages back to LRU and therefore no progress is made and scan_movable_pages finds same set of pages over and over again. Fix both cases by explicitly checking HWPoisoned pages before we even try to get reference on the page, try to unmap it if it is still mapped. As explained by Naoya: : Hwpoison code never unmapped those for no big reason because : Ksm pages never dominate memory, so we simply didn't have strong : motivation to save the pages. Also put WARN_ON(PageLRU) in case there is a race and we can hit LRU HWPoison pages which shouldn't happen but I couldn't convince myself about that. Naoya has noted the following: : Theoretically no such gurantee, because try_to_unmap() doesn't have a : guarantee of success and then memory_failure() returns immediately : when hwpoison_user_mappings fails. : Or the following code (comes after hwpoison_user_mappings block) also impli= : es : that the target page can still have PageLRU flag. : : /* : * Torn down by someone else? : */ : if (PageLRU(p) && !PageSwapCache(p) && p->mapping =3D=3D NULL) { : action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED); : res =3D -EBUSY; : goto out; : } : : So I think it's OK to keep "if (WARN_ON(PageLRU(page)))" block in : current version of your patch. Link: http://lkml.kernel.org/r/20181206120135.14079-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko(a)suse.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.com> Debugged-by: Oscar Salvador <osalvador(a)suse.com> Tested-by: Oscar Salvador <osalvador(a)suse.com> Acked-by: David Hildenbrand <david(a)redhat.com> Acked-by: Naoya Horiguchi <n-horiguchi(a)ah.jp.nec.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/mm/memory_hotplug.c~hwpoison-memory_hotplug-allow-hwpoisoned-pages-to-be-offlined +++ a/mm/memory_hotplug.c @@ -34,6 +34,7 @@ #include <linux/hugetlb.h> #include <linux/memblock.h> #include <linux/compaction.h> +#include <linux/rmap.h> #include <asm/tlbflush.h> @@ -1368,6 +1369,21 @@ do_migrate_range(unsigned long start_pfn pfn = page_to_pfn(compound_head(page)) + hpage_nr_pages(page) - 1; + /* + * HWPoison pages have elevated reference counts so the migration would + * fail on them. It also doesn't make any sense to migrate them in the + * first place. Still try to unmap such a page in case it is still mapped + * (e.g. current hwpoison implementation doesn't unmap KSM pages but keep + * the unmap as the catch all safety net). + */ + if (PageHWPoison(page)) { + if (WARN_ON(PageLRU(page))) + isolate_lru_page(page); + if (page_mapped(page)) + try_to_unmap(page, TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS); + continue; + } + if (!get_page_unless_zero(page)) continue; /* _

6 years, 9 months

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[patch 112/167] zram: fix double free backing device

by akpm＠linux-foundation.org

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> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky(a)gmail.com> Reviewed-by: Joey Pabalinas <joeypabalinas(a)gmail.com> Cc: <stable(a)vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- 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); _

6 years, 9 months

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[patch 090/167] mm, hmm: mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, hmm: mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL At Maintainer Summit, Greg brought up a topic I proposed around EXPORT_SYMBOL_GPL usage. The motivation was considerations for when EXPORT_SYMBOL_GPL is warranted and the criteria for taking the exceptional step of reclassifying an existing export. Specifically, I wanted to make the case that although the line is fuzzy and hard to specify in abstract terms, it is nonetheless clear that devm_memremap_pages() and HMM (Heterogeneous Memory Management) have crossed it. The devm_memremap_pages() facility should have been EXPORT_SYMBOL_GPL from the beginning, and HMM as a derivative of that functionality should have naturally picked up that designation as well. Contrary to typical rules, the HMM infrastructure was merged upstream with zero in-tree consumers. There was a promise at the time that those users would be merged "soon", but it has been over a year with no drivers arriving. While the Nouveau driver is about to belatedly make good on that promise it is clear that HMM was targeted first and foremost at an out-of-tree consumer. HMM is derived from devm_memremap_pages(), a facility Christoph and I spearheaded to support persistent memory. It combines a device lifetime model with a dynamically created 'struct page' / memmap array for any physical address range. It enables coordination and control of the many code paths in the kernel built to interact with memory via 'struct page' objects. With HMM the integration goes even deeper by allowing device drivers to hook and manipulate page fault and page free events. One interpretation of when EXPORT_SYMBOL is suitable is when it is exporting stable and generic leaf functionality. The devm_memremap_pages() facility continues to see expanding use cases, peer-to-peer DMA being the most recent, with no clear end date when it will stop attracting reworks and semantic changes. It is not suitable to export devm_memremap_pages() as a stable 3rd party driver API due to the fact that it is still changing and manipulates core behavior. Moreover, it is not in the best interest of the long term development of the core memory management subsystem to permit any external driver to effectively define its own system-wide memory management policies with no encouragement to engage with upstream. I am also concerned that HMM was designed in a way to minimize further engagement with the core-MM. That, with these hooks in place, device-drivers are free to implement their own policies without much consideration for whether and how the core-MM could grow to meet that need. Going forward not only should HMM be EXPORT_SYMBOL_GPL, but the core-MM should be allowed the opportunity and stimulus to change and address these new use cases as first class functionality. Original changelog: hmm_devmem_add(), and hmm_devmem_add_resource() duplicated devm_memremap_pages() and are now simple now wrappers around the core facility to inject a dev_pagemap instance into the global pgmap_radix and hook page-idle events. The devm_memremap_pages() interface is base infrastructure for HMM. HMM has more and deeper ties into the kernel memory management implementation than base ZONE_DEVICE which is itself a EXPORT_SYMBOL_GPL facility. Originally, the HMM page structure creation routines copied the devm_memremap_pages() code and reused ZONE_DEVICE. A cleanup to unify the implementations was discussed during the initial review: http://lkml.iu.edu/hypermail/linux/kernel/1701.2/00812.html Recent work to extend devm_memremap_pages() for the peer-to-peer-DMA facility enabled this cleanup to move forward. In addition to the integration with devm_memremap_pages() HMM depends on other GPL-only symbols: mmu_notifier_unregister_no_release percpu_ref region_intersects __class_create It goes further to consume / indirectly expose functionality that is not exported to any other driver: alloc_pages_vma walk_page_range HMM is derived from devm_memremap_pages(), and extends deep core-kernel fundamentals. Similar to devm_memremap_pages(), mark its entry points EXPORT_SYMBOL_GPL(). [logang(a)deltatee.com: PCI/P2PDMA: match interface changes to devm_memremap_pages()] Link: http://lkml.kernel.org/r/20181130225911.2900-1-logang@deltatee.com Link: http://lkml.kernel.org/r/154275560565.76910.15919297436557795278.stgit@dwil… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Signed-off-by: Logan Gunthorpe <logang(a)deltatee.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Cc: Logan Gunthorpe <logang(a)deltatee.com> Cc: "Jérôme Glisse" <jglisse(a)redhat.com> Cc: Balbir Singh <bsingharora(a)gmail.com>, Cc: Michal Hocko <mhocko(a)suse.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Benjamin Herrenschmidt <benh(a)kernel.crashing.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/drivers/pci/p2pdma.c~mm-hmm-mark-hmm_devmem_add-add_resource-export_symbol_gpl +++ a/drivers/pci/p2pdma.c @@ -82,10 +82,8 @@ static void pci_p2pdma_percpu_release(st complete_all(&p2p->devmap_ref_done); } -static void pci_p2pdma_percpu_kill(void *data) +static void pci_p2pdma_percpu_kill(struct percpu_ref *ref) { - struct percpu_ref *ref = data; - /* * pci_p2pdma_add_resource() may be called multiple times * by a driver and may register the percpu_kill devm action multiple @@ -198,6 +196,7 @@ int pci_p2pdma_add_resource(struct pci_d pgmap->type = MEMORY_DEVICE_PCI_P2PDMA; pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) - pci_resource_start(pdev, bar); + pgmap->kill = pci_p2pdma_percpu_kill; addr = devm_memremap_pages(&pdev->dev, pgmap); if (IS_ERR(addr)) { @@ -211,11 +210,6 @@ int pci_p2pdma_add_resource(struct pci_d if (error) goto pgmap_free; - error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_percpu_kill, - &pdev->p2pdma->devmap_ref); - if (error) - goto pgmap_free; - pci_info(pdev, "added peer-to-peer DMA memory %pR\n", &pgmap->res); --- a/mm/hmm.c~mm-hmm-mark-hmm_devmem_add-add_resource-export_symbol_gpl +++ a/mm/hmm.c @@ -1110,7 +1110,7 @@ struct hmm_devmem *hmm_devmem_add(const return result; return devmem; } -EXPORT_SYMBOL(hmm_devmem_add); +EXPORT_SYMBOL_GPL(hmm_devmem_add); struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, struct device *device, @@ -1164,7 +1164,7 @@ struct hmm_devmem *hmm_devmem_add_resour return result; return devmem; } -EXPORT_SYMBOL(hmm_devmem_add_resource); +EXPORT_SYMBOL_GPL(hmm_devmem_add_resource); /* * A device driver that wants to handle multiple devices memory through a _

6 years, 9 months

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[patch 089/167] mm, hmm: replace hmm_devmem_pages_create() with devm_memremap_pages()

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, hmm: replace hmm_devmem_pages_create() with devm_memremap_pages() e8d513483300 "memremap: change devm_memremap_pages interface to use struct dev_pagemap" refactored devm_memremap_pages() to allow a dev_pagemap instance to be supplied. Passing in a dev_pagemap interface simplifies the design of pgmap type drivers in that they can rely on container_of() to lookup any private data associated with the given dev_pagemap instance. In addition to the cleanups this also gives hmm users multi-order-radix improvements that arrived with commit ab1b597ee0e4 "mm, devm_memremap_pages: use multi-order radix for ZONE_DEVICE lookups" As part of the conversion to the devm_memremap_pages() method of handling the percpu_ref relative to when pages are put, the percpu_ref completion needs to move to hmm_devmem_ref_exit(). See 71389703839e ("mm, zone_device: Replace {get, put}_zone_device_page...") for details. Link: http://lkml.kernel.org/r/154275560053.76910.10870962637383152392.stgit@dwil… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Reviewed-by: Jérôme Glisse <jglisse(a)redhat.com> Acked-by: Balbir Singh <bsingharora(a)gmail.com> Cc: Logan Gunthorpe <logang(a)deltatee.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/mm/hmm.c~mm-hmm-replace-hmm_devmem_pages_create-with-devm_memremap_pages +++ a/mm/hmm.c @@ -986,17 +986,16 @@ static void hmm_devmem_ref_exit(void *da struct hmm_devmem *devmem; devmem = container_of(ref, struct hmm_devmem, ref); + wait_for_completion(&devmem->completion); percpu_ref_exit(ref); } -static void hmm_devmem_ref_kill(void *data) +static void hmm_devmem_ref_kill(struct percpu_ref *ref) { - struct percpu_ref *ref = data; struct hmm_devmem *devmem; devmem = container_of(ref, struct hmm_devmem, ref); percpu_ref_kill(ref); - wait_for_completion(&devmem->completion); } static int hmm_devmem_fault(struct vm_area_struct *vma, @@ -1019,154 +1018,6 @@ static void hmm_devmem_free(struct page devmem->ops->free(devmem, page); } -static DEFINE_MUTEX(hmm_devmem_lock); -static RADIX_TREE(hmm_devmem_radix, GFP_KERNEL); - -static void hmm_devmem_radix_release(struct resource *resource) -{ - resource_size_t key; - - mutex_lock(&hmm_devmem_lock); - for (key = resource->start; - key <= resource->end; - key += PA_SECTION_SIZE) - radix_tree_delete(&hmm_devmem_radix, key >> PA_SECTION_SHIFT); - mutex_unlock(&hmm_devmem_lock); -} - -static void hmm_devmem_release(void *data) -{ - struct hmm_devmem *devmem = data; - struct resource *resource = devmem->resource; - unsigned long start_pfn, npages; - struct zone *zone; - struct page *page; - - /* pages are dead and unused, undo the arch mapping */ - start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT; - npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT; - - page = pfn_to_page(start_pfn); - zone = page_zone(page); - - mem_hotplug_begin(); - if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) - __remove_pages(zone, start_pfn, npages, NULL); - else - arch_remove_memory(start_pfn << PAGE_SHIFT, - npages << PAGE_SHIFT, NULL); - mem_hotplug_done(); - - hmm_devmem_radix_release(resource); -} - -static int hmm_devmem_pages_create(struct hmm_devmem *devmem) -{ - resource_size_t key, align_start, align_size, align_end; - struct device *device = devmem->device; - int ret, nid, is_ram; - - align_start = devmem->resource->start & ~(PA_SECTION_SIZE - 1); - align_size = ALIGN(devmem->resource->start + - resource_size(devmem->resource), - PA_SECTION_SIZE) - align_start; - - is_ram = region_intersects(align_start, align_size, - IORESOURCE_SYSTEM_RAM, - IORES_DESC_NONE); - if (is_ram == REGION_MIXED) { - WARN_ONCE(1, "%s attempted on mixed region %pr\n", - __func__, devmem->resource); - return -ENXIO; - } - if (is_ram == REGION_INTERSECTS) - return -ENXIO; - - if (devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY) - devmem->pagemap.type = MEMORY_DEVICE_PUBLIC; - else - devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; - - devmem->pagemap.res = *devmem->resource; - devmem->pagemap.page_fault = hmm_devmem_fault; - devmem->pagemap.page_free = hmm_devmem_free; - devmem->pagemap.dev = devmem->device; - devmem->pagemap.ref = &devmem->ref; - devmem->pagemap.data = devmem; - - mutex_lock(&hmm_devmem_lock); - align_end = align_start + align_size - 1; - for (key = align_start; key <= align_end; key += PA_SECTION_SIZE) { - struct hmm_devmem *dup; - - dup = radix_tree_lookup(&hmm_devmem_radix, - key >> PA_SECTION_SHIFT); - if (dup) { - dev_err(device, "%s: collides with mapping for %s\n", - __func__, dev_name(dup->device)); - mutex_unlock(&hmm_devmem_lock); - ret = -EBUSY; - goto error; - } - ret = radix_tree_insert(&hmm_devmem_radix, - key >> PA_SECTION_SHIFT, - devmem); - if (ret) { - dev_err(device, "%s: failed: %d\n", __func__, ret); - mutex_unlock(&hmm_devmem_lock); - goto error_radix; - } - } - mutex_unlock(&hmm_devmem_lock); - - nid = dev_to_node(device); - if (nid < 0) - nid = numa_mem_id(); - - mem_hotplug_begin(); - /* - * For device private memory we call add_pages() as we only need to - * allocate and initialize struct page for the device memory. More- - * over the device memory is un-accessible thus we do not want to - * create a linear mapping for the memory like arch_add_memory() - * would do. - * - * For device public memory, which is accesible by the CPU, we do - * want the linear mapping and thus use arch_add_memory(). - */ - if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC) - ret = arch_add_memory(nid, align_start, align_size, NULL, - false); - else - ret = add_pages(nid, align_start >> PAGE_SHIFT, - align_size >> PAGE_SHIFT, NULL, false); - if (ret) { - mem_hotplug_done(); - goto error_add_memory; - } - move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], - align_start >> PAGE_SHIFT, - align_size >> PAGE_SHIFT, NULL); - mem_hotplug_done(); - - /* - * Initialization of the pages has been deferred until now in order - * to allow us to do the work while not holding the hotplug lock. - */ - memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], - align_start >> PAGE_SHIFT, - align_size >> PAGE_SHIFT, &devmem->pagemap); - - return 0; - -error_add_memory: - untrack_pfn(NULL, PHYS_PFN(align_start), align_size); -error_radix: - hmm_devmem_radix_release(devmem->resource); -error: - return ret; -} - /* * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory * @@ -1190,6 +1041,7 @@ struct hmm_devmem *hmm_devmem_add(const { struct hmm_devmem *devmem; resource_size_t addr; + void *result; int ret; dev_pagemap_get_ops(); @@ -1244,14 +1096,18 @@ struct hmm_devmem *hmm_devmem_add(const devmem->pfn_last = devmem->pfn_first + (resource_size(devmem->resource) >> PAGE_SHIFT); - ret = hmm_devmem_pages_create(devmem); - if (ret) - return ERR_PTR(ret); - - ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem); - if (ret) - return ERR_PTR(ret); + devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; + devmem->pagemap.res = *devmem->resource; + devmem->pagemap.page_fault = hmm_devmem_fault; + devmem->pagemap.page_free = hmm_devmem_free; + devmem->pagemap.altmap_valid = false; + devmem->pagemap.ref = &devmem->ref; + devmem->pagemap.data = devmem; + devmem->pagemap.kill = hmm_devmem_ref_kill; + result = devm_memremap_pages(devmem->device, &devmem->pagemap); + if (IS_ERR(result)) + return result; return devmem; } EXPORT_SYMBOL(hmm_devmem_add); @@ -1261,6 +1117,7 @@ struct hmm_devmem *hmm_devmem_add_resour struct resource *res) { struct hmm_devmem *devmem; + void *result; int ret; if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY) @@ -1293,19 +1150,18 @@ struct hmm_devmem *hmm_devmem_add_resour devmem->pfn_last = devmem->pfn_first + (resource_size(devmem->resource) >> PAGE_SHIFT); - ret = hmm_devmem_pages_create(devmem); - if (ret) - return ERR_PTR(ret); - - ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem); - if (ret) - return ERR_PTR(ret); - - ret = devm_add_action_or_reset(device, hmm_devmem_ref_kill, - &devmem->ref); - if (ret) - return ERR_PTR(ret); + devmem->pagemap.type = MEMORY_DEVICE_PUBLIC; + devmem->pagemap.res = *devmem->resource; + devmem->pagemap.page_fault = hmm_devmem_fault; + devmem->pagemap.page_free = hmm_devmem_free; + devmem->pagemap.altmap_valid = false; + devmem->pagemap.ref = &devmem->ref; + devmem->pagemap.data = devmem; + devmem->pagemap.kill = hmm_devmem_ref_kill; + result = devm_memremap_pages(devmem->device, &devmem->pagemap); + if (IS_ERR(result)) + return result; return devmem; } EXPORT_SYMBOL(hmm_devmem_add_resource); _

6 years, 9 months

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[patch 088/167] mm, hmm: use devm semantics for hmm_devmem_{add, remove}

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, hmm: use devm semantics for hmm_devmem_{add, remove} devm semantics arrange for resources to be torn down when device-driver-probe fails or when device-driver-release completes. Similar to devm_memremap_pages() there is no need to support an explicit remove operation when the users properly adhere to devm semantics. Note that devm_kzalloc() automatically handles allocating node-local memory. Link: http://lkml.kernel.org/r/154275559545.76910.9186690723515469051.stgit@dwill… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Reviewed-by: Jérôme Glisse <jglisse(a)redhat.com> Cc: "Jérôme Glisse" <jglisse(a)redhat.com> Cc: Logan Gunthorpe <logang(a)deltatee.com> Cc: Balbir Singh <bsingharora(a)gmail.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/include/linux/hmm.h~mm-hmm-use-devm-semantics-for-hmm_devmem_add-remove +++ a/include/linux/hmm.h @@ -512,8 +512,7 @@ struct hmm_devmem { * enough and allocate struct page for it. * * The device driver can wrap the hmm_devmem struct inside a private device - * driver struct. The device driver must call hmm_devmem_remove() before the - * device goes away and before freeing the hmm_devmem struct memory. + * driver struct. */ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, struct device *device, @@ -521,7 +520,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, struct device *device, struct resource *res); -void hmm_devmem_remove(struct hmm_devmem *devmem); /* * hmm_devmem_page_set_drvdata - set per-page driver data field --- a/mm/hmm.c~mm-hmm-use-devm-semantics-for-hmm_devmem_add-remove +++ a/mm/hmm.c @@ -987,7 +987,6 @@ static void hmm_devmem_ref_exit(void *da devmem = container_of(ref, struct hmm_devmem, ref); percpu_ref_exit(ref); - devm_remove_action(devmem->device, &hmm_devmem_ref_exit, data); } static void hmm_devmem_ref_kill(void *data) @@ -998,7 +997,6 @@ static void hmm_devmem_ref_kill(void *da devmem = container_of(ref, struct hmm_devmem, ref); percpu_ref_kill(ref); wait_for_completion(&devmem->completion); - devm_remove_action(devmem->device, &hmm_devmem_ref_kill, data); } static int hmm_devmem_fault(struct vm_area_struct *vma, @@ -1036,7 +1034,7 @@ static void hmm_devmem_radix_release(str mutex_unlock(&hmm_devmem_lock); } -static void hmm_devmem_release(struct device *dev, void *data) +static void hmm_devmem_release(void *data) { struct hmm_devmem *devmem = data; struct resource *resource = devmem->resource; @@ -1044,11 +1042,6 @@ static void hmm_devmem_release(struct de struct zone *zone; struct page *page; - if (percpu_ref_tryget_live(&devmem->ref)) { - dev_WARN(dev, "%s: page mapping is still live!\n", __func__); - percpu_ref_put(&devmem->ref); - } - /* pages are dead and unused, undo the arch mapping */ start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT; npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT; @@ -1174,19 +1167,6 @@ error: return ret; } -static int hmm_devmem_match(struct device *dev, void *data, void *match_data) -{ - struct hmm_devmem *devmem = data; - - return devmem->resource == match_data; -} - -static void hmm_devmem_pages_remove(struct hmm_devmem *devmem) -{ - devres_release(devmem->device, &hmm_devmem_release, - &hmm_devmem_match, devmem->resource); -} - /* * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory * @@ -1214,8 +1194,7 @@ struct hmm_devmem *hmm_devmem_add(const dev_pagemap_get_ops(); - devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), - GFP_KERNEL, dev_to_node(device)); + devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL); if (!devmem) return ERR_PTR(-ENOMEM); @@ -1229,11 +1208,11 @@ struct hmm_devmem *hmm_devmem_add(const ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release, 0, GFP_KERNEL); if (ret) - goto error_percpu_ref; + return ERR_PTR(ret); - ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref); + ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, &devmem->ref); if (ret) - goto error_devm_add_action; + return ERR_PTR(ret); size = ALIGN(size, PA_SECTION_SIZE); addr = min((unsigned long)iomem_resource.end, @@ -1253,16 +1232,12 @@ struct hmm_devmem *hmm_devmem_add(const devmem->resource = devm_request_mem_region(device, addr, size, dev_name(device)); - if (!devmem->resource) { - ret = -ENOMEM; - goto error_no_resource; - } + if (!devmem->resource) + return ERR_PTR(-ENOMEM); break; } - if (!devmem->resource) { - ret = -ERANGE; - goto error_no_resource; - } + if (!devmem->resource) + return ERR_PTR(-ERANGE); devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY; devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; @@ -1271,28 +1246,13 @@ struct hmm_devmem *hmm_devmem_add(const ret = hmm_devmem_pages_create(devmem); if (ret) - goto error_pages; - - devres_add(device, devmem); + return ERR_PTR(ret); - ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref); - if (ret) { - hmm_devmem_remove(devmem); + ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem); + if (ret) return ERR_PTR(ret); - } return devmem; - -error_pages: - devm_release_mem_region(device, devmem->resource->start, - resource_size(devmem->resource)); -error_no_resource: -error_devm_add_action: - hmm_devmem_ref_kill(&devmem->ref); - hmm_devmem_ref_exit(&devmem->ref); -error_percpu_ref: - devres_free(devmem); - return ERR_PTR(ret); } EXPORT_SYMBOL(hmm_devmem_add); @@ -1308,8 +1268,7 @@ struct hmm_devmem *hmm_devmem_add_resour dev_pagemap_get_ops(); - devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), - GFP_KERNEL, dev_to_node(device)); + devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL); if (!devmem) return ERR_PTR(-ENOMEM); @@ -1323,12 +1282,12 @@ struct hmm_devmem *hmm_devmem_add_resour ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release, 0, GFP_KERNEL); if (ret) - goto error_percpu_ref; + return ERR_PTR(ret); - ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref); + ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, + &devmem->ref); if (ret) - goto error_devm_add_action; - + return ERR_PTR(ret); devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; devmem->pfn_last = devmem->pfn_first + @@ -1336,60 +1295,22 @@ struct hmm_devmem *hmm_devmem_add_resour ret = hmm_devmem_pages_create(devmem); if (ret) - goto error_devm_add_action; + return ERR_PTR(ret); - devres_add(device, devmem); + ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem); + if (ret) + return ERR_PTR(ret); - ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref); - if (ret) { - hmm_devmem_remove(devmem); + ret = devm_add_action_or_reset(device, hmm_devmem_ref_kill, + &devmem->ref); + if (ret) return ERR_PTR(ret); - } return devmem; - -error_devm_add_action: - hmm_devmem_ref_kill(&devmem->ref); - hmm_devmem_ref_exit(&devmem->ref); -error_percpu_ref: - devres_free(devmem); - return ERR_PTR(ret); } EXPORT_SYMBOL(hmm_devmem_add_resource); /* - * hmm_devmem_remove() - remove device memory (kill and free ZONE_DEVICE) - * - * @devmem: hmm_devmem struct use to track and manage the ZONE_DEVICE memory - * - * This will hot-unplug memory that was hotplugged by hmm_devmem_add on behalf - * of the device driver. It will free struct page and remove the resource that - * reserved the physical address range for this device memory. - */ -void hmm_devmem_remove(struct hmm_devmem *devmem) -{ - resource_size_t start, size; - struct device *device; - bool cdm = false; - - if (!devmem) - return; - - device = devmem->device; - start = devmem->resource->start; - size = resource_size(devmem->resource); - - cdm = devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY; - hmm_devmem_ref_kill(&devmem->ref); - hmm_devmem_ref_exit(&devmem->ref); - hmm_devmem_pages_remove(devmem); - - if (!cdm) - devm_release_mem_region(device, start, size); -} -EXPORT_SYMBOL(hmm_devmem_remove); - -/* * A device driver that wants to handle multiple devices memory through a * single fake device can use hmm_device to do so. This is purely a helper * and it is not needed to make use of any HMM functionality. _

6 years, 9 months

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[patch 087/167] mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support In preparation for consolidating all ZONE_DEVICE enabling via devm_memremap_pages(), teach it how to handle the constraints of MEMORY_DEVICE_PRIVATE ranges. [jglisse(a)redhat.com: call move_pfn_range_to_zone for MEMORY_DEVICE_PRIVATE] Link: http://lkml.kernel.org/r/154275559036.76910.12434636179931292607.stgit@dwil… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Reviewed-by: Jérôme Glisse <jglisse(a)redhat.com> Acked-by: Christoph Hellwig <hch(a)lst.de> Reported-by: Logan Gunthorpe <logang(a)deltatee.com> Reviewed-by: Logan Gunthorpe <logang(a)deltatee.com> Cc: Balbir Singh <bsingharora(a)gmail.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/kernel/memremap.c~mm-devm_memremap_pages-add-memory_device_private-support +++ a/kernel/memremap.c @@ -98,9 +98,15 @@ static void devm_memremap_pages_release( - align_start; mem_hotplug_begin(); - arch_remove_memory(align_start, align_size, pgmap->altmap_valid ? - &pgmap->altmap : NULL); - kasan_remove_zero_shadow(__va(align_start), align_size); + if (pgmap->type == MEMORY_DEVICE_PRIVATE) { + pfn = align_start >> PAGE_SHIFT; + __remove_pages(page_zone(pfn_to_page(pfn)), pfn, + align_size >> PAGE_SHIFT, NULL); + } else { + arch_remove_memory(align_start, align_size, + pgmap->altmap_valid ? &pgmap->altmap : NULL); + kasan_remove_zero_shadow(__va(align_start), align_size); + } mem_hotplug_done(); untrack_pfn(NULL, PHYS_PFN(align_start), align_size); @@ -187,17 +193,40 @@ void *devm_memremap_pages(struct device goto err_pfn_remap; mem_hotplug_begin(); - error = kasan_add_zero_shadow(__va(align_start), align_size); - if (error) { - mem_hotplug_done(); - goto err_kasan; + + /* + * For device private memory we call add_pages() as we only need to + * allocate and initialize struct page for the device memory. More- + * over the device memory is un-accessible thus we do not want to + * create a linear mapping for the memory like arch_add_memory() + * would do. + * + * For all other device memory types, which are accessible by + * the CPU, we do want the linear mapping and thus use + * arch_add_memory(). + */ + if (pgmap->type == MEMORY_DEVICE_PRIVATE) { + error = add_pages(nid, align_start >> PAGE_SHIFT, + align_size >> PAGE_SHIFT, NULL, false); + } else { + error = kasan_add_zero_shadow(__va(align_start), align_size); + if (error) { + mem_hotplug_done(); + goto err_kasan; + } + + error = arch_add_memory(nid, align_start, align_size, altmap, + false); + } + + if (!error) { + struct zone *zone; + + zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE]; + move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT, + align_size >> PAGE_SHIFT, altmap); } - error = arch_add_memory(nid, align_start, align_size, altmap, false); - if (!error) - move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], - align_start >> PAGE_SHIFT, - align_size >> PAGE_SHIFT, altmap); mem_hotplug_done(); if (error) goto err_add_memory; _

6 years, 9 months

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[patch 086/167] mm, devm_memremap_pages: fix shutdown handling

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, devm_memremap_pages: fix shutdown handling The last step before devm_memremap_pages() returns success is to allocate a release action, devm_memremap_pages_release(), to tear the entire setup down. However, the result from devm_add_action() is not checked. Checking the error from devm_add_action() is not enough. The api currently relies on the fact that the percpu_ref it is using is killed by the time the devm_memremap_pages_release() is run. Rather than continue this awkward situation, offload the responsibility of killing the percpu_ref to devm_memremap_pages_release() directly. This allows devm_memremap_pages() to do the right thing relative to init failures and shutdown. Without this change we could fail to register the teardown of devm_memremap_pages(). The likelihood of hitting this failure is tiny as small memory allocations almost always succeed. However, the impact of the failure is large given any future reconfiguration, or disable/enable, of an nvdimm namespace will fail forever as subsequent calls to devm_memremap_pages() will fail to setup the pgmap_radix since there will be stale entries for the physical address range. An argument could be made to require that the ->kill() operation be set in the @pgmap arg rather than passed in separately. However, it helps code readability, tracking the lifetime of a given instance, to be able to grep the kill routine directly at the devm_memremap_pages() call site. Link: http://lkml.kernel.org/r/154275558526.76910.7535251937849268605.stgit@dwill… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Fixes: e8d513483300 ("memremap: change devm_memremap_pages interface...") Reviewed-by: "Jérôme Glisse" <jglisse(a)redhat.com> Reported-by: Logan Gunthorpe <logang(a)deltatee.com> Reviewed-by: Logan Gunthorpe <logang(a)deltatee.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Cc: Balbir Singh <bsingharora(a)gmail.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/drivers/dax/pmem.c~mm-devm_memremap_pages-fix-shutdown-handling +++ a/drivers/dax/pmem.c @@ -48,9 +48,8 @@ static void dax_pmem_percpu_exit(void *d percpu_ref_exit(ref); } -static void dax_pmem_percpu_kill(void *data) +static void dax_pmem_percpu_kill(struct percpu_ref *ref) { - struct percpu_ref *ref = data; struct dax_pmem *dax_pmem = to_dax_pmem(ref); dev_dbg(dax_pmem->dev, "trace\n"); @@ -112,17 +111,10 @@ static int dax_pmem_probe(struct device } dax_pmem->pgmap.ref = &dax_pmem->ref; + dax_pmem->pgmap.kill = dax_pmem_percpu_kill; addr = devm_memremap_pages(dev, &dax_pmem->pgmap); - if (IS_ERR(addr)) { - devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); - percpu_ref_exit(&dax_pmem->ref); + if (IS_ERR(addr)) return PTR_ERR(addr); - } - - rc = devm_add_action_or_reset(dev, dax_pmem_percpu_kill, - &dax_pmem->ref); - if (rc) - return rc; /* adjust the dax_region resource to the start of data */ memcpy(&res, &dax_pmem->pgmap.res, sizeof(res)); --- a/drivers/nvdimm/pmem.c~mm-devm_memremap_pages-fix-shutdown-handling +++ a/drivers/nvdimm/pmem.c @@ -309,8 +309,11 @@ static void pmem_release_queue(void *q) blk_cleanup_queue(q); } -static void pmem_freeze_queue(void *q) +static void pmem_freeze_queue(struct percpu_ref *ref) { + struct request_queue *q; + + q = container_of(ref, typeof(*q), q_usage_counter); blk_freeze_queue_start(q); } @@ -402,6 +405,7 @@ static int pmem_attach_disk(struct devic pmem->pfn_flags = PFN_DEV; pmem->pgmap.ref = &q->q_usage_counter; + pmem->pgmap.kill = pmem_freeze_queue; if (is_nd_pfn(dev)) { if (setup_pagemap_fsdax(dev, &pmem->pgmap)) return -ENOMEM; @@ -427,13 +431,6 @@ static int pmem_attach_disk(struct devic memcpy(&bb_res, &nsio->res, sizeof(bb_res)); } - /* - * At release time the queue must be frozen before - * devm_memremap_pages is unwound - */ - if (devm_add_action_or_reset(dev, pmem_freeze_queue, q)) - return -ENOMEM; - if (IS_ERR(addr)) return PTR_ERR(addr); pmem->virt_addr = addr; --- a/include/linux/memremap.h~mm-devm_memremap_pages-fix-shutdown-handling +++ a/include/linux/memremap.h @@ -111,6 +111,7 @@ typedef void (*dev_page_free_t)(struct p * @altmap: pre-allocated/reserved memory for vmemmap allocations * @res: physical address range covered by @ref * @ref: reference count that pins the devm_memremap_pages() mapping + * @kill: callback to transition @ref to the dead state * @dev: host device of the mapping for debug * @data: private data pointer for page_free() * @type: memory type: see MEMORY_* in memory_hotplug.h @@ -122,6 +123,7 @@ struct dev_pagemap { bool altmap_valid; struct resource res; struct percpu_ref *ref; + void (*kill)(struct percpu_ref *ref); struct device *dev; void *data; enum memory_type type; --- a/kernel/memremap.c~mm-devm_memremap_pages-fix-shutdown-handling +++ a/kernel/memremap.c @@ -88,14 +88,10 @@ static void devm_memremap_pages_release( resource_size_t align_start, align_size; unsigned long pfn; + pgmap->kill(pgmap->ref); for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); - if (percpu_ref_tryget_live(pgmap->ref)) { - dev_WARN(dev, "%s: page mapping is still live!\n", __func__); - percpu_ref_put(pgmap->ref); - } - /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) @@ -116,7 +112,7 @@ static void devm_memremap_pages_release( /** * devm_memremap_pages - remap and provide memmap backing for the given resource * @dev: hosting device for @res - * @pgmap: pointer to a struct dev_pgmap + * @pgmap: pointer to a struct dev_pagemap * * Notes: * 1/ At a minimum the res, ref and type members of @pgmap must be initialized @@ -125,11 +121,8 @@ static void devm_memremap_pages_release( * 2/ The altmap field may optionally be initialized, in which case altmap_valid * must be set to true * - * 3/ pgmap.ref must be 'live' on entry and 'dead' before devm_memunmap_pages() - * time (or devm release event). The expected order of events is that ref has - * been through percpu_ref_kill() before devm_memremap_pages_release(). The - * wait for the completion of all references being dropped and - * percpu_ref_exit() must occur after devm_memremap_pages_release(). + * 3/ pgmap->ref must be 'live' on entry and will be killed at + * devm_memremap_pages_release() time, or if this routine fails. * * 4/ res is expected to be a host memory range that could feasibly be * treated as a "System RAM" range, i.e. not a device mmio range, but @@ -145,6 +138,9 @@ void *devm_memremap_pages(struct device pgprot_t pgprot = PAGE_KERNEL; int error, nid, is_ram; + if (!pgmap->ref || !pgmap->kill) + return ERR_PTR(-EINVAL); + align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; @@ -170,12 +166,10 @@ void *devm_memremap_pages(struct device if (is_ram != REGION_DISJOINT) { WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__, is_ram == REGION_MIXED ? "mixed" : "ram", res); - return ERR_PTR(-ENXIO); + error = -ENXIO; + goto err_array; } - if (!pgmap->ref) - return ERR_PTR(-EINVAL); - pgmap->dev = dev; error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(res->start), @@ -217,7 +211,10 @@ void *devm_memremap_pages(struct device align_size >> PAGE_SHIFT, pgmap); percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap)); - devm_add_action(dev, devm_memremap_pages_release, pgmap); + error = devm_add_action_or_reset(dev, devm_memremap_pages_release, + pgmap); + if (error) + return ERR_PTR(error); return __va(res->start); @@ -228,6 +225,7 @@ void *devm_memremap_pages(struct device err_pfn_remap: pgmap_array_delete(res); err_array: + pgmap->kill(pgmap->ref); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(devm_memremap_pages); --- a/tools/testing/nvdimm/test/iomap.c~mm-devm_memremap_pages-fix-shutdown-handling +++ a/tools/testing/nvdimm/test/iomap.c @@ -104,13 +104,26 @@ void *__wrap_devm_memremap(struct device } EXPORT_SYMBOL(__wrap_devm_memremap); +static void nfit_test_kill(void *_pgmap) +{ + struct dev_pagemap *pgmap = _pgmap; + + pgmap->kill(pgmap->ref); +} + void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) { resource_size_t offset = pgmap->res.start; struct nfit_test_resource *nfit_res = get_nfit_res(offset); - if (nfit_res) + if (nfit_res) { + int rc; + + rc = devm_add_action_or_reset(dev, nfit_test_kill, pgmap); + if (rc) + return ERR_PTR(rc); return nfit_res->buf + offset - nfit_res->res.start; + } return devm_memremap_pages(dev, pgmap); } EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages); _

6 years, 9 months

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[patch 085/167] mm, devm_memremap_pages: kill mapping "System RAM" support

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, devm_memremap_pages: kill mapping "System RAM" support Given the fact that devm_memremap_pages() requires a percpu_ref that is torn down by devm_memremap_pages_release() the current support for mapping RAM is broken. Support for remapping "System RAM" has been broken since the beginning and there is no existing user of this this code path, so just kill the support and make it an explicit error. This cleanup also simplifies a follow-on patch to fix the error path when setting a devm release action for devm_memremap_pages_release() fails. Link: http://lkml.kernel.org/r/154275557997.76910.14689813630968180480.stgit@dwil… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Reviewed-by: "Jérôme Glisse" <jglisse(a)redhat.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Reviewed-by: Logan Gunthorpe <logang(a)deltatee.com> Cc: Balbir Singh <bsingharora(a)gmail.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/kernel/memremap.c~mm-devm_memremap_pages-kill-mapping-system-ram-support +++ a/kernel/memremap.c @@ -167,15 +167,12 @@ void *devm_memremap_pages(struct device is_ram = region_intersects(align_start, align_size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); - if (is_ram == REGION_MIXED) { - WARN_ONCE(1, "%s attempted on mixed region %pr\n", - __func__, res); + if (is_ram != REGION_DISJOINT) { + WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__, + is_ram == REGION_MIXED ? "mixed" : "ram", res); return ERR_PTR(-ENXIO); } - if (is_ram == REGION_INTERSECTS) - return __va(res->start); - if (!pgmap->ref) return ERR_PTR(-EINVAL); _

6 years, 9 months

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[patch 084/167] mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL_GPL

by akpm＠linux-foundation.org

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL_GPL devm_memremap_pages() is a facility that can create struct page entries for any arbitrary range and give drivers the ability to subvert core aspects of page management. Specifically the facility is tightly integrated with the kernel's memory hotplug functionality. It injects an altmap argument deep into the architecture specific vmemmap implementation to allow allocating from specific reserved pages, and it has Linux specific assumptions about page structure reference counting relative to get_user_pages() and get_user_pages_fast(). It was an oversight and a mistake that this was not marked EXPORT_SYMBOL_GPL from the outset. Again, devm_memremap_pagex() exposes and relies upon core kernel internal assumptions and will continue to evolve along with 'struct page', memory hotplug, and support for new memory types / topologies. Only an in-kernel GPL-only driver is expected to keep up with this ongoing evolution. This interface, and functionality derived from this interface, is not suitable for kernel-external drivers. Link: http://lkml.kernel.org/r/154275557457.76910.16923571232582744134.stgit@dwil… Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Acked-by: Michal Hocko <mhocko(a)suse.com> Cc: "Jérôme Glisse" <jglisse(a)redhat.com> Cc: Balbir Singh <bsingharora(a)gmail.com> Cc: Logan Gunthorpe <logang(a)deltatee.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/kernel/memremap.c~mm-devm_memremap_pages-mark-devm_memremap_pages-export_symbol_gpl +++ a/kernel/memremap.c @@ -233,7 +233,7 @@ void *devm_memremap_pages(struct device err_array: return ERR_PTR(error); } -EXPORT_SYMBOL(devm_memremap_pages); +EXPORT_SYMBOL_GPL(devm_memremap_pages); unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) { --- a/tools/testing/nvdimm/test/iomap.c~mm-devm_memremap_pages-mark-devm_memremap_pages-export_symbol_gpl +++ a/tools/testing/nvdimm/test/iomap.c @@ -113,7 +113,7 @@ void *__wrap_devm_memremap_pages(struct return nfit_res->buf + offset - nfit_res->res.start; return devm_memremap_pages(dev, pgmap); } -EXPORT_SYMBOL(__wrap_devm_memremap_pages); +EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages); pfn_t __wrap_phys_to_pfn_t(phys_addr_t addr, unsigned long flags) { _

6 years, 9 months

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[folded-merged] hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race-v3.patch removed from -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race-v3 has been removed from the -mm tree. Its filename was hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race-v3.patch This patch was dropped because it was folded into hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race.patch ------------------------------------------------------ From: Mike Kravetz <mike.kravetz(a)oracle.com> Subject: hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race-v3 Incorporated suggestions from Kirill. Code change to hold i_mmap_rwsem for duration of copy in copy_hugetlb_page_range. Took i_mmap_rwsem in hugetlbfs_evict_inode to be consistent with other callers. Other changes were to documentation/comments. Link: http://lkml.kernel.org/r/20181222223013.22193-3-mike.kravetz@oracle.com Cc: <stable(a)vger.kernel.org> Fixes: ebed4bfc8da8 ("hugetlb: fix absurd HugePages_Rsvd") Signed-off-by: Mike Kravetz <mike.kravetz(a)oracle.com> Cc: Andrea Arcangeli <aarcange(a)redhat.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar(a)linux.vnet.ibm.com> Cc: Davidlohr Bueso <dave(a)stgolabs.net> Cc: Hugh Dickins <hughd(a)google.com> Cc: "Kirill A . Shutemov" <kirill.shutemov(a)linux.intel.com> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Naoya Horiguchi <n-horiguchi(a)ah.jp.nec.com> Cc: Prakash Sangappa <prakash.sangappa(a)oracle.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- --- a/fs/hugetlbfs/inode.c~hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race-v3 +++ a/fs/hugetlbfs/inode.c @@ -462,9 +462,20 @@ static void remove_inode_hugepages(struc static void hugetlbfs_evict_inode(struct inode *inode) { + struct address_space *mapping = inode->i_mapping; struct resv_map *resv_map; + /* + * The vfs layer guarantees that there are no other users of this + * inode. Therefore, it would be safe to call remove_inode_hugepages + * without holding i_mmap_rwsem. We acquire and hold here to be + * consistent with other callers. Since there will be no contention + * on the semaphore, overhead is negligible. + */ + i_mmap_lock_write(mapping); remove_inode_hugepages(inode, 0, LLONG_MAX); + i_mmap_unlock_write(mapping); + resv_map = (struct resv_map *)inode->i_mapping->private_data; /* root inode doesn't have the resv_map, so we should check it */ if (resv_map) _ Patches currently in -mm which might be from mike.kravetz(a)oracle.com are hugetlbfs-use-i_mmap_rwsem-for-more-pmd-sharing-synchronization.patch hugetlbfs-use-i_mmap_rwsem-to-fix-page-fault-truncate-race.patch

6 years, 9 months

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