On Wed, 1 Jun 2022 15:13:54 -0700 Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > On Wed, Jun 1, 2022 at 3:09 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > The patch titled > > Subject: mm-drop-oom-code-from-exit_mmap-fix > > has been added to the -mm mm-unstable branch. Its filename is > > mm-drop-oom-code-from-exit_mmap-fix.patch > > > > This patch will shortly appear at > > https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-drop-oom-code-from-exit_mmap-fix.patch > > > > This patch will later appear in the mm-unstable branch at > > git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm > > > > Before you just go and hit "reply", please: > > a) Consider who else should be cc'ed > > b) Prefer to cc a suitable mailing list as well > > c) Ideally: find the original patch on the mailing list and do a > > reply-to-all to that, adding suitable additional cc's > > > > *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** > > > > The -mm tree is included into linux-next via the mm-everything > > branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm > > and is updated there every 2-3 working days > > > > ------------------------------------------------------ > > From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > Subject: mm-drop-oom-code-from-exit_mmap-fix > > Date: Wed Jun 1 03:07:59 PM PDT 2022 > > > > fix it for presense of mapletree patchset, per Suren > > Andrew, could we also restore the mmap_lock_read/write retaking? It > does make a difference for parallel memory reaping. > If you want I can post a v3 with more explanation about that and also > a separate patchset applied over maple-tree branch (if you have it > separately). Should I? Like this? --- a/mm/mmap.c~mm-drop-oom-code-from-exit_mmap-fix-fix +++ a/mm/mmap.c @@ -3171,13 +3171,13 @@ 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; } @@ -3187,6 +3187,7 @@ 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 @@ -3194,6 +3195,7 @@ 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_unlock(mm); free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb); _ void exit_mmap(struct mm_struct *mm) { struct mmu_gather tlb; struct vm_area_struct *vma; unsigned long nr_accounted = 0; MA_STATE(mas, &mm->mm_mt, 0, 0); int count = 0; /* mm's last user has gone, and its about to be pulled down */ mmu_notifier_release(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_read_unlock(mm); return; } lru_add_drain(); flush_cache_mm(mm); tlb_gather_mmu_fullmm(&tlb, 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 * because the memory has been already freed. Do not bother checking * mm_is_oom_victim because setting a bit unconditionally is cheaper. */ set_bit(MMF_OOM_SKIP, &mm->flags); mmap_write_unlock(mm); free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb); /* * Walk the list again, actually closing and freeing it, with preemption * enabled, without holding any MM locks besides the unreachable * mmap_write_lock. */ do { if (vma->vm_flags & VM_ACCOUNT) nr_accounted += vma_pages(vma); remove_vma(vma); count++; cond_resched(); } while ((vma = mas_find(&mas, ULONG_MAX)) != NULL); BUG_ON(count != mm->map_count); trace_exit_mmap(mm); __mt_destroy(&mm->mm_mt); mmap_write_unlock(mm); vm_unacct_memory(nr_accounted); }
