kernel/linux.git/mm/memory.c, branch v5.10.257

mm: fix apply_to_existing_page_range()

2025-05-02T05:41:09+00:00

commit a995199384347261bb3f21b2e171fa7f988bd2f8 upstream. In the case of apply_to_existing_page_range(), apply_to_pte_range() is reached with 'create' set to false. When !create, the loop over the PTE page table is broken. apply_to_pte_range() will only move to the next PTE entry if 'create' is true or if the current entry is not pte_none(). This means that the user of apply_to_existing_page_range() will not have 'fn' called for any entries after the first pte_none() in the PTE page table. Fix the loop logic in apply_to_pte_range(). There are no known runtime issues from this, but the fix is trivial enough for stable@ even without a known buggy user. Link: https://lkml.kernel.org/r/20250409094043.1629234-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Fixes: be1db4753ee6 ("mm/memory.c: add apply_to_existing_page_range() helper") Cc: Daniel Axtens Cc: David Hildenbrand Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Kirill A. Shutemov Signed-off-by: Greg Kroah-Hartman

mm: avoid leaving partial pfn mappings around in error case

2024-11-08T15:22:03+00:00

commit 79a61cc3fc0466ad2b7b89618a6157785f0293b3 upstream. As Jann points out, PFN mappings are special, because unlike normal memory mappings, there is no lifetime information associated with the mapping - it is just a raw mapping of PFNs with no reference counting of a 'struct page'. That's all very much intentional, but it does mean that it's easy to mess up the cleanup in case of errors. Yes, a failed mmap() will always eventually clean up any partial mappings, but without any explicit lifetime in the page table mapping itself, it's very easy to do the error handling in the wrong order. In particular, it's easy to mistakenly free the physical backing store before the page tables are actually cleaned up and (temporarily) have stale dangling PTE entries. To make this situation less error-prone, just make sure that any partial pfn mapping is torn down early, before any other error handling. Reported-and-tested-by: Jann Horn Cc: Andrew Morton Cc: Jason Gunthorpe Cc: Simona Vetter Signed-off-by: Linus Torvalds Signed-off-by: Harshvardhan Jha Signed-off-by: Greg Kroah-Hartman

mm: add remap_pfn_range_notrack

2024-11-08T15:22:03+00:00

commit 74ffa5a3e68504dd289135b1cf0422c19ffb3f2e upstream. Patch series "add remap_pfn_range_notrack instead of reinventing it in i915", v2. i915 has some reason to want to avoid the track_pfn_remap overhead in remap_pfn_range. Add a function to the core VM to do just that rather than reinventing the functionality poorly in the driver. Note that the remap_io_sg path does get exercises when using Xorg on my Thinkpad X1, so this should be considered lightly tested, I've not managed to hit the remap_io_mapping path at all. This patch (of 4): Add a version of remap_pfn_range that does not call track_pfn_range. This will be used to fix horrible abuses of VM internals in the i915 driver. Link: https://lkml.kernel.org/r/20210326055505.1424432-1-hch@lst.de Link: https://lkml.kernel.org/r/20210326055505.1424432-2-hch@lst.de Signed-off-by: Christoph Hellwig Acked-by: Daniel Vetter Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Rodrigo Vivi Cc: Chris Wilson Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Harshvardhan Jha Signed-off-by: Greg Kroah-Hartman

x86/mm/pat: fix VM_PAT handling in COW mappings

2024-04-13T10:59:56+00:00

commit 04c35ab3bdae7fefbd7c7a7355f29fa03a035221 upstream. PAT handling won't do the right thing in COW mappings: the first PTE (or, in fact, all PTEs) can be replaced during write faults to point at anon folios. Reliably recovering the correct PFN and cachemode using follow_phys() from PTEs will not work in COW mappings. Using follow_phys(), we might just get the address+protection of the anon folio (which is very wrong), or fail on swap/nonswap entries, failing follow_phys() and triggering a WARN_ON_ONCE() in untrack_pfn() and track_pfn_copy(), not properly calling free_pfn_range(). In free_pfn_range(), we either wouldn't call memtype_free() or would call it with the wrong range, possibly leaking memory. To fix that, let's update follow_phys() to refuse returning anon folios, and fallback to using the stored PFN inside vma->vm_pgoff for COW mappings if we run into that. We will now properly handle untrack_pfn() with COW mappings, where we don't need the cachemode. We'll have to fail fork()->track_pfn_copy() if the first page was replaced by an anon folio, though: we'd have to store the cachemode in the VMA to make this work, likely growing the VMA size. For now, lets keep it simple and let track_pfn_copy() just fail in that case: it would have failed in the past with swap/nonswap entries already, and it would have done the wrong thing with anon folios. Simple reproducer to trigger the WARN_ON_ONCE() in untrack_pfn(): <--- C reproducer ---> #include #include #include #include int main(void) { struct io_uring_params p = {}; int ring_fd; size_t size; char *map; ring_fd = io_uring_setup(1, &p); if (ring_fd < 0) { perror("io_uring_setup"); return 1; } size = p.sq_off.array + p.sq_entries * sizeof(unsigned); /* Map the submission queue ring MAP_PRIVATE */ map = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, ring_fd, IORING_OFF_SQ_RING); if (map == MAP_FAILED) { perror("mmap"); return 1; } /* We have at least one page. Let's COW it. */ *map = 0; pause(); return 0; } <--- C reproducer ---> On a system with 16 GiB RAM and swap configured: # ./iouring & # memhog 16G # killall iouring [ 301.552930] ------------[ cut here ]------------ [ 301.553285] WARNING: CPU: 7 PID: 1402 at arch/x86/mm/pat/memtype.c:1060 untrack_pfn+0xf4/0x100 [ 301.553989] Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_g [ 301.558232] CPU: 7 PID: 1402 Comm: iouring Not tainted 6.7.5-100.fc38.x86_64 #1 [ 301.558772] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebu4 [ 301.559569] RIP: 0010:untrack_pfn+0xf4/0x100 [ 301.559893] Code: 75 c4 eb cf 48 8b 43 10 8b a8 e8 00 00 00 3b 6b 28 74 b8 48 8b 7b 30 e8 ea 1a f7 000 [ 301.561189] RSP: 0018:ffffba2c0377fab8 EFLAGS: 00010282 [ 301.561590] RAX: 00000000ffffffea RBX: ffff9208c8ce9cc0 RCX: 000000010455e047 [ 301.562105] RDX: 07fffffff0eb1e0a RSI: 0000000000000000 RDI: ffff9208c391d200 [ 301.562628] RBP: 0000000000000000 R08: ffffba2c0377fab8 R09: 0000000000000000 [ 301.563145] R10: ffff9208d2292d50 R11: 0000000000000002 R12: 00007fea890e0000 [ 301.563669] R13: 0000000000000000 R14: ffffba2c0377fc08 R15: 0000000000000000 [ 301.564186] FS: 0000000000000000(0000) GS:ffff920c2fbc0000(0000) knlGS:0000000000000000 [ 301.564773] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 301.565197] CR2: 00007fea88ee8a20 CR3: 00000001033a8000 CR4: 0000000000750ef0 [ 301.565725] PKRU: 55555554 [ 301.565944] Call Trace: [ 301.566148] [ 301.566325] ? untrack_pfn+0xf4/0x100 [ 301.566618] ? __warn+0x81/0x130 [ 301.566876] ? untrack_pfn+0xf4/0x100 [ 301.567163] ? report_bug+0x171/0x1a0 [ 301.567466] ? handle_bug+0x3c/0x80 [ 301.567743] ? exc_invalid_op+0x17/0x70 [ 301.568038] ? asm_exc_invalid_op+0x1a/0x20 [ 301.568363] ? untrack_pfn+0xf4/0x100 [ 301.568660] ? untrack_pfn+0x65/0x100 [ 301.568947] unmap_single_vma+0xa6/0xe0 [ 301.569247] unmap_vmas+0xb5/0x190 [ 301.569532] exit_mmap+0xec/0x340 [ 301.569801] __mmput+0x3e/0x130 [ 301.570051] do_exit+0x305/0xaf0 ... Link: https://lkml.kernel.org/r/20240403212131.929421-3-david@redhat.com Signed-off-by: David Hildenbrand Reported-by: Wupeng Ma Closes: https://lkml.kernel.org/r/20240227122814.3781907-1-mawupeng1@huawei.com Fixes: b1a86e15dc03 ("x86, pat: remove the dependency on 'vm_pgoff' in track/untrack pfn vma routines") Fixes: 5899329b1910 ("x86: PAT: implement track/untrack of pfnmap regions for x86 - v3") Acked-by: Ingo Molnar Cc: Dave Hansen Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Signed-off-by: Andrew Morton Signed-off-by: David Hildenbrand Signed-off-by: Greg Kroah-Hartman

mm: fix unmap_mapping_range high bits shift bug

2024-01-15T17:48:06+00:00

commit 9eab0421fa94a3dde0d1f7e36ab3294fc306c99d upstream. The bug happens when highest bit of holebegin is 1, suppose holebegin is 0x8000000111111000, after shift, hba would be 0xfff8000000111111, then vma_interval_tree_foreach would look it up fail or leads to the wrong result. error call seq e.g.: - mmap(..., offset=0x8000000111111000) |- syscall(mmap, ... unsigned long, off): |- ksys_mmap_pgoff( ... , off >> PAGE_SHIFT); here pgoff is correctly shifted to 0x8000000111111, but pass 0x8000000111111000 as holebegin to unmap would then cause terrible result, as shown below: - unmap_mapping_range(..., loff_t const holebegin) |- pgoff_t hba = holebegin >> PAGE_SHIFT; /* hba = 0xfff8000000111111 unexpectedly */ The issue happens in Heterogeneous computing, where the device(e.g. gpu) and host share the same virtual address space. A simple workflow pattern which hit the issue is: /* host */ 1. userspace first mmap a file backed VA range with specified offset. e.g. (offset=0x800..., mmap return: va_a) 2. write some data to the corresponding sys page e.g. (va_a = 0xAABB) /* device */ 3. gpu workload touches VA, triggers gpu fault and notify the host. /* host */ 4. reviced gpu fault notification, then it will: 4.1 unmap host pages and also takes care of cpu tlb (use unmap_mapping_range with offset=0x800...) 4.2 migrate sys page to device 4.3 setup device page table and resolve device fault. /* device */ 5. gpu workload continued, it accessed va_a and got 0xAABB. 6. gpu workload continued, it wrote 0xBBCC to va_a. /* host */ 7. userspace access va_a, as expected, it will: 7.1 trigger cpu vm fault. 7.2 driver handling fault to migrate gpu local page to host. 8. userspace then could correctly get 0xBBCC from va_a 9. done But in step 4.1, if we hit the bug this patch mentioned, then userspace would never trigger cpu fault, and still get the old value: 0xAABB. Making holebegin unsigned first fixes the bug. Link: https://lkml.kernel.org/r/20231220052839.26970-1-jiajun.xie.sh@gmail.com Signed-off-by: Jiajun Xie Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/memory: add non-anonymous page check in the copy_present_page()

2022-11-03T14:57:50+00:00

The vma->anon_vma of the child process may be NULL because the entire vma does not contain anonymous pages. In this case, a BUG will occur when the copy_present_page() passes a copy of a non-anonymous page of that vma to the page_add_new_anon_rmap() to set up new anonymous rmap. ------------[ cut here ]------------ kernel BUG at mm/rmap.c:1044! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: CPU: 2 PID: 3617 Comm: test Not tainted 5.10.149 #1 Hardware name: linux,dummy-virt (DT) pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) pc : __page_set_anon_rmap+0xbc/0xf8 lr : __page_set_anon_rmap+0xbc/0xf8 sp : ffff800014c1b870 x29: ffff800014c1b870 x28: 0000000000000001 x27: 0000000010100073 x26: ffff1d65c517baa8 x25: ffff1d65cab0f000 x24: ffff1d65c416d800 x23: ffff1d65cab5f248 x22: 0000000020000000 x21: 0000000000000001 x20: 0000000000000000 x19: fffffe75970023c0 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : ffffc3096d5fb858 x8 : 0000000000000000 x7 : 0000000000000011 x6 : ffff5a5c9089c000 x5 : 0000000000020000 x4 : ffff5a5c9089c000 x3 : ffffc3096d200000 x2 : ffffc3096e8d0000 x1 : ffff1d65ca3da740 x0 : 0000000000000000 Call trace: __page_set_anon_rmap+0xbc/0xf8 page_add_new_anon_rmap+0x1e0/0x390 copy_pte_range+0xd00/0x1248 copy_page_range+0x39c/0x620 dup_mmap+0x2e0/0x5a8 dup_mm+0x78/0x140 copy_process+0x918/0x1a20 kernel_clone+0xac/0x638 __do_sys_clone+0x78/0xb0 __arm64_sys_clone+0x30/0x40 el0_svc_common.constprop.0+0xb0/0x308 do_el0_svc+0x48/0xb8 el0_svc+0x24/0x38 el0_sync_handler+0x160/0x168 el0_sync+0x180/0x1c0 Code: 97f8ff85 f9400294 17ffffeb 97f8ff82 (d4210000) ---[ end trace a972347688dc9bd4 ]--- Kernel panic - not syncing: Oops - BUG: Fatal exception SMP: stopping secondary CPUs Kernel Offset: 0x43095d200000 from 0xffff800010000000 PHYS_OFFSET: 0xffffe29a80000000 CPU features: 0x08200022,61806082 Memory Limit: none ---[ end Kernel panic - not syncing: Oops - BUG: Fatal exception ]--- This problem has been fixed by the commit ("mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap()"), but still exists in the linux-5.10.y branch. This patch is not applicable to this version because of the large version differences. Therefore, fix it by adding non-anonymous page check in the copy_present_page(). Cc: stable@vger.kernel.org Fixes: 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes") Signed-off-by: Yuanzheng Song Acked-by: Peter Xu Signed-off-by: Greg Kroah-Hartman

mm: split huge PUD on wp_huge_pud fallback

2022-07-21T19:19:59+00:00

commit 14c99d65941538aa33edd8dc7b1bbbb593c324a2 upstream. Currently the implementation will split the PUD when a fallback is taken inside the create_huge_pud function. This isn't where it should be done: the splitting should be done in wp_huge_pud, just like it's done for PMDs. Reason being that if a callback is taken during create, there is no PUD yet so nothing to split, whereas if a fallback is taken when encountering a write protection fault there is something to split. It looks like this was the original intention with the commit where the splitting was introduced, but somehow it got moved to the wrong place between v1 and v2 of the patch series. Rebase mistake perhaps. Link: https://lkml.kernel.org/r/6f48d622eb8bce1ae5dd75327b0b73894a2ec407.camel@amazon.com Fixes: 327e9fd48972 ("mm: Split huge pages on write-notify or COW") Signed-off-by: James Gowans Reviewed-by: Thomas Hellström Cc: Christian König Cc: Jan H. Schönherr Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm: hugetlb: fix missing cache flush in copy_huge_page_from_user()

2022-05-15T18:00:09+00:00

commit e763243cc6cb1fcc720ec58cfd6e7c35ae90a479 upstream. userfaultfd calls copy_huge_page_from_user() which does not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Fix this issue by flushing dcache in copy_huge_page_from_user(). Link: https://lkml.kernel.org/r/20220210123058.79206-4-songmuchun@bytedance.com Fixes: fa4d75c1de13 ("userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support") Signed-off-by: Muchun Song Reviewed-by: Mike Kravetz Cc: Axel Rasmussen Cc: David Rientjes Cc: Fam Zheng Cc: Kirill A. Shutemov Cc: Lars Persson Cc: Peter Xu Cc: Xiongchun Duan Cc: Zi Yan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: don't skip swap entry even if zap_details specified

2022-04-13T19:01:10+00:00

commit 5abfd71d936a8aefd9f9ccd299dea7a164a5d455 upstream. Patch series "mm: Rework zap ptes on swap entries", v5. Patch 1 should fix a long standing bug for zap_pte_range() on zap_details usage. The risk is we could have some swap entries skipped while we should have zapped them. Migration entries are not the major concern because file backed memory always zap in the pattern that "first time without page lock, then re-zap with page lock" hence the 2nd zap will always make sure all migration entries are already recovered. However there can be issues with real swap entries got skipped errornoously. There's a reproducer provided in commit message of patch 1 for that. Patch 2-4 are cleanups that are based on patch 1. After the whole patchset applied, we should have a very clean view of zap_pte_range(). Only patch 1 needs to be backported to stable if necessary. This patch (of 4): The "details" pointer shouldn't be the token to decide whether we should skip swap entries. For example, when the callers specified details->zap_mapping==NULL, it means the user wants to zap all the pages (including COWed pages), then we need to look into swap entries because there can be private COWed pages that was swapped out. Skipping some swap entries when details is non-NULL may lead to wrongly leaving some of the swap entries while we should have zapped them. A reproducer of the problem: ===8<=== #define _GNU_SOURCE /* See feature_test_macros(7) */ #include #include #include #include #include int page_size; int shmem_fd; char *buffer; void main(void) { int ret; char val; page_size = getpagesize(); shmem_fd = memfd_create("test", 0); assert(shmem_fd >= 0); ret = ftruncate(shmem_fd, page_size * 2); assert(ret == 0); buffer = mmap(NULL, page_size * 2, PROT_READ | PROT_WRITE, MAP_PRIVATE, shmem_fd, 0); assert(buffer != MAP_FAILED); /* Write private page, swap it out */ buffer[page_size] = 1; madvise(buffer, page_size * 2, MADV_PAGEOUT); /* This should drop private buffer[page_size] already */ ret = ftruncate(shmem_fd, page_size); assert(ret == 0); /* Recover the size */ ret = ftruncate(shmem_fd, page_size * 2); assert(ret == 0); /* Re-read the data, it should be all zero */ val = buffer[page_size]; if (val == 0) printf("Good\n"); else printf("BUG\n"); } ===8<=== We don't need to touch up the pmd path, because pmd never had a issue with swap entries. For example, shmem pmd migration will always be split into pte level, and same to swapping on anonymous. Add another helper should_zap_cows() so that we can also check whether we should zap private mappings when there's no page pointer specified. This patch drops that trick, so we handle swap ptes coherently. Meanwhile we should do the same check upon migration entry, hwpoison entry and genuine swap entries too. To be explicit, we should still remember to keep the private entries if even_cows==false, and always zap them when even_cows==true. The issue seems to exist starting from the initial commit of git. [peterx@redhat.com: comment tweaks] Link: https://lkml.kernel.org/r/20220217060746.71256-2-peterx@redhat.com Link: https://lkml.kernel.org/r/20220217060746.71256-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20220216094810.60572-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20220216094810.60572-2-peterx@redhat.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Peter Xu Reviewed-by: John Hubbard Cc: David Hildenbrand Cc: Hugh Dickins Cc: Alistair Popple Cc: Andrea Arcangeli Cc: "Kirill A . Shutemov" Cc: Matthew Wilcox Cc: Vlastimil Babka Cc: Yang Shi Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm,hwpoison: unmap poisoned page before invalidation

2022-04-08T12:39:54+00:00

commit 3149c79f3cb0e2e3bafb7cfadacec090cbd250d3 upstream. In some cases it appears the invalidation of a hwpoisoned page fails because the page is still mapped in another process. This can cause a program to be continuously restarted and die when it page faults on the page that was not invalidated. Avoid that problem by unmapping the hwpoisoned page when we find it. Another issue is that sometimes we end up oopsing in finish_fault, if the code tries to do something with the now-NULL vmf->page. I did not hit this error when submitting the previous patch because there are several opportunities for alloc_set_pte to bail out before accessing vmf->page, and that apparently happened on those systems, and most of the time on other systems, too. However, across several million systems that error does occur a handful of times a day. It can be avoided by returning VM_FAULT_NOPAGE which will cause do_read_fault to return before calling finish_fault. Link: https://lkml.kernel.org/r/20220325161428.5068d97e@imladris.surriel.com Fixes: e53ac7374e64 ("mm: invalidate hwpoison page cache page in fault path") Signed-off-by: Rik van Riel Reviewed-by: Miaohe Lin Tested-by: Naoya Horiguchi Reviewed-by: Oscar Salvador Cc: Mel Gorman Cc: Johannes Weiner Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman