From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, hannes@cmpxchg.org,
kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
mhocko@kernel.org, mm-commits@vger.kernel.org,
songmuchun@bytedance.com, stable@vger.kernel.org,
tglx@linutronix.de, torvalds@linux-foundation.org,
vdavydov.dev@gmail.com, zhengqi.arch@bytedance.com
Subject: [patch 14/15] mm: fix the deadlock in finish_fault()
Date: Fri, 23 Jul 2021 15:50:41 -0700 [thread overview]
Message-ID: <20210723225041.VB3Yq9fkx%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210723154926.c6cda0f262b1990b950a5886@linux-foundation.org>
From: Qi Zheng <zhengqi.arch@bytedance.com>
Subject: mm: fix the deadlock in finish_fault()
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") rework the relevant code but ignore 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>
---
mm/memory.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/mm/memory.c~mm-fix-the-deadlock-in-finish_fault
+++ a/mm/memory.c
@@ -4026,8 +4026,17 @@ vm_fault_t finish_fault(struct vm_fault
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() */
_
next prev parent reply other threads:[~2021-07-23 22:50 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 22:49 incoming Andrew Morton
2021-07-23 22:50 ` [patch 01/15] userfaultfd: do not untag user pointers Andrew Morton
2021-07-23 22:50 ` [patch 02/15] selftest: use mmap instead of posix_memalign to allocate memory Andrew Morton
2021-07-23 22:50 ` [patch 03/15] kfence: defer kfence_test_init to ensure that kunit debugfs is created Andrew Morton
2021-07-23 22:50 ` [patch 04/15] kfence: move the size check to the beginning of __kfence_alloc() Andrew Morton
2021-07-23 22:50 ` [patch 05/15] kfence: skip all GFP_ZONEMASK allocations Andrew Morton
2021-07-23 22:50 ` [patch 06/15] mm: call flush_dcache_page() in memcpy_to_page() and memzero_page() Andrew Morton
2021-07-24 6:59 ` Christoph Hellwig
2021-07-24 16:23 ` Matthew Wilcox
2021-07-23 22:50 ` [patch 07/15] mm: use kmap_local_page in memzero_page Andrew Morton
2021-07-23 22:50 ` [patch 08/15] mm: page_alloc: fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction Andrew Morton
2021-07-23 22:50 ` [patch 09/15] memblock: make for_each_mem_range() traverse MEMBLOCK_HOTPLUG regions Andrew Morton
2021-07-23 22:50 ` [patch 10/15] writeback, cgroup: remove wb from offline list before releasing refcnt Andrew Morton
2021-07-23 22:50 ` [patch 11/15] writeback, cgroup: do not reparent dax inodes Andrew Morton
2021-07-23 22:50 ` [patch 12/15] mm/secretmem: wire up ->set_page_dirty Andrew Morton
2021-07-23 22:50 ` [patch 13/15] mm: mmap_lock: fix disabling preemption directly Andrew Morton
2021-07-23 22:50 ` Andrew Morton [this message]
2021-07-23 22:50 ` [patch 15/15] hugetlbfs: fix mount mode command line processing Andrew Morton
2021-07-24 1:41 ` Al Viro
2021-07-26 5:22 ` Andrew Morton
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