diff options
| author | Qi Zheng <zhengqi.arch@bytedance.com> | 2021-07-23 15:50:41 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-28 14:37:40 +0200 |
| commit | 4861f6d3b90f81b4c5e3817c9092885962b369bc (patch) | |
| tree | cfe85e1d961a6806c211587d8cd40a1c8a011210 /mm | |
| parent | 5d4b4d2e3c8d5bc3bf62f94a594cd02ca7e7b65c (diff) | |
mm: fix the deadlock in finish_fault()
commit e4dc3489143f84f7ed30be58b886bb6772f229b9 upstream.
Commit 63f3655f9501 ("mm, memcg: fix reclaim deadlock with writeback")
fix the following ABBA deadlock by pre-allocating the pte page table
without holding the page lock.
lock_page(A)
SetPageWriteback(A)
unlock_page(A)
lock_page(B)
lock_page(B)
pte_alloc_one
shrink_page_list
wait_on_page_writeback(A)
SetPageWriteback(B)
unlock_page(B)
# flush A, B to clear the writeback
Commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault()
codepaths") reworked the relevant code but ignored this race. This will
cause the deadlock above to appear again, so fix it.
Link: https://lkml.kernel.org/r/20210721074849.57004-1-zhengqi.arch@bytedance.com
Fixes: f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c index 3fdba3ec69c8..f2293c0df33f 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3891,8 +3891,17 @@ vm_fault_t finish_fault(struct vm_fault *vmf) return ret; } - if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) + if (vmf->prealloc_pte) { + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (likely(pmd_none(*vmf->pmd))) { + mm_inc_nr_ptes(vma->vm_mm); + pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); + vmf->prealloc_pte = NULL; + } + spin_unlock(vmf->ptl); + } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) { return VM_FAULT_OOM; + } } /* See comment in handle_pte_fault() */ |