From: Yu Zhao yuzhao@google.com
stable inclusion from stable-v6.6.11 commit e73022d600175f2d88010438b91897c624e33c64 bugzilla: https://gitee.com/openeuler/kernel/issues/I99TJK
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
--------------------------------
commit c28ac3c7eb945fee6e20f47d576af68fdff1392a upstream.
Special VMAs like VM_PFNMAP can contain anon pages from COW. There isn't much profit in doing lookaround on them. Besides, they can trigger the pte_special() warning in get_pte_pfn().
Skip them in lru_gen_look_around().
Link: https://lkml.kernel.org/r/20231223045647.1566043-1-yuzhao@google.com Fixes: 018ee47f1489 ("mm: multi-gen LRU: exploit locality in rmap") Signed-off-by: Yu Zhao yuzhao@google.com Reported-by: syzbot+03fd9b3f71641f0ebf2d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/000000000000f9ff00060d14c256@google.com/ Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: ZhangPeng zhangpeng362@huawei.com --- mm/vmscan.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index 93097be6f10d..c4660bb6f182 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4676,6 +4676,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) int young = 0; pte_t *pte = pvmw->pte; unsigned long addr = pvmw->address; + struct vm_area_struct *vma = pvmw->vma; struct folio *folio = pfn_folio(pvmw->pfn); bool can_swap = !folio_is_file_lru(folio); struct mem_cgroup *memcg = folio_memcg(folio); @@ -4690,11 +4691,15 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) if (spin_is_contended(pvmw->ptl)) return;
+ /* exclude special VMAs containing anon pages from COW */ + if (vma->vm_flags & VM_SPECIAL) + return; + /* avoid taking the LRU lock under the PTL when possible */ walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL;
- start = max(addr & PMD_MASK, pvmw->vma->vm_start); - end = min(addr | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1; + start = max(addr & PMD_MASK, vma->vm_start); + end = min(addr | ~PMD_MASK, vma->vm_end - 1) + 1;
if (end - start > MIN_LRU_BATCH * PAGE_SIZE) { if (addr - start < MIN_LRU_BATCH * PAGE_SIZE / 2) @@ -4719,7 +4724,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) unsigned long pfn; pte_t ptent = ptep_get(pte + i);
- pfn = get_pte_pfn(ptent, pvmw->vma, addr); + pfn = get_pte_pfn(ptent, vma, addr); if (pfn == -1) continue;
@@ -4730,7 +4735,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) if (!folio) continue;
- if (!ptep_test_and_clear_young(pvmw->vma, addr, pte + i)) + if (!ptep_test_and_clear_young(vma, addr, pte + i)) VM_WARN_ON_ONCE(true);
young++;