From e9c24812058a797c27580c09536d602810f90996 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 1 Jun 2022 15:17:52 -0700 Subject: [PATCH] mm-drop-oom-code-from-exit_mmap-fix-fix restore Suren's mmap_read_lock() optimization Cc: Suren Baghdasaryan Cc: Liam Howlett Signed-off-by: Andrew Morton --- mm/mmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 9f5d25d0974b..03e533bb5343 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3130,13 +3130,13 @@ void exit_mmap(struct mm_struct *mm) /* mm's last user has gone, and its about to be pulled down */ mmu_notifier_release(mm); - mmap_write_lock(mm); + mmap_read_lock(mm); arch_exit_mmap(mm); vma = mas_find(&mas, ULONG_MAX); if (!vma) { /* Can happen if dup_mmap() received an OOM */ - mmap_write_unlock(mm); + mmap_read_unlock(mm); return; } @@ -3146,6 +3146,7 @@ void exit_mmap(struct mm_struct *mm) /* update_hiwater_rss(mm) here? but nobody should be looking */ /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX); + mmap_read_unlock(mm); /* * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper @@ -3153,6 +3154,7 @@ void exit_mmap(struct mm_struct *mm) * mm_is_oom_victim because setting a bit unconditionally is cheaper. */ set_bit(MMF_OOM_SKIP, &mm->flags); + mmap_write_lock(mm); free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb); -- 2.50.1