From: Michal Hocko <mhocko@suse.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, rientjes@google.com,
willy@infradead.org, hannes@cmpxchg.org, guro@fb.com,
riel@surriel.com, minchan@kernel.org, kirill@shutemov.name,
aarcange@redhat.com, christian@brauner.io, hch@infradead.org,
oleg@redhat.com, david@redhat.com, jannh@google.com,
shakeelb@google.com, luto@kernel.org,
christian.brauner@ubuntu.com, fweimer@redhat.com,
jengelh@inai.de, timmurray@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, kernel-team@android.com
Subject: [PATCH 4/3] mm: drop MMF_OOM_SKIP from exit_mmap
Date: Thu, 9 Dec 2021 10:12:10 +0100 [thread overview]
Message-ID: <YbHIaq9a0CtqRulE@dhcp22.suse.cz> (raw)
In-Reply-To: <20211208212211.2860249-1-surenb@google.com>
Do we want this on top?
----
From 58b04ae6dc97b0105ea2651daca55cf2386f69b4 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Thu, 9 Dec 2021 10:07:51 +0100
Subject: [PATCH] mm: drop MMF_OOM_SKIP from exit_mmap
MMF_OOM_SKIP used to play a synchronization role between exit_mmap and
oom repear in the past. Since the exclusive mmap_sem is held in
exit_mmap to cover all destructive operations the flag synchronization
is not needed anymore and we can safely drop it. Just make sure that
mm->mmap is set to NULL so that nobody will access the freed vma list.
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
mm/mmap.c | 23 +----------------------
1 file changed, 1 insertion(+), 22 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index f4e09d390a07..0d6af9d89aa8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3129,28 +3129,6 @@ void exit_mmap(struct mm_struct *mm)
/* mm's last user has gone, and its about to be pulled down */
mmu_notifier_release(mm);
- if (unlikely(mm_is_oom_victim(mm))) {
- /*
- * Manually reap the mm to free as much memory as possible.
- * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
- * this mm from further consideration. Taking mm->mmap_lock for
- * write after setting MMF_OOM_SKIP will guarantee that the oom
- * reaper will not run on this mm again after mmap_lock is
- * dropped.
- *
- * Nothing can be holding mm->mmap_lock here and the above call
- * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
- * __oom_reap_task_mm() will not block.
- *
- * This needs to be done before calling unlock_range(),
- * which clears VM_LOCKED, otherwise the oom reaper cannot
- * reliably test it.
- */
- (void)__oom_reap_task_mm(mm);
-
- set_bit(MMF_OOM_SKIP, &mm->flags);
- }
-
mmap_write_lock(mm);
if (mm->locked_vm)
unlock_range(mm->mmap, ULONG_MAX);
@@ -3180,6 +3158,7 @@ void exit_mmap(struct mm_struct *mm)
vma = remove_vma(vma);
cond_resched();
}
+ mm->mmap = NULL;
mmap_write_unlock(mm);
vm_unacct_memory(nr_accounted);
}
--
2.30.2
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-12-09 9:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 21:22 [PATCH v4 1/3] mm: protect free_pgtables with mmap_lock write lock in exit_mmap Suren Baghdasaryan
2021-12-08 21:22 ` [PATCH v4 2/3] mm: document locking restrictions for vm_operations_struct::close Suren Baghdasaryan
2021-12-09 8:55 ` Michal Hocko
2021-12-08 21:22 ` [PATCH v4 3/3] mm/oom_kill: allow process_mrelease to run under mmap_lock protection Suren Baghdasaryan
2021-12-09 8:59 ` Michal Hocko
2021-12-09 19:03 ` Suren Baghdasaryan
2021-12-09 8:55 ` [PATCH v4 1/3] mm: protect free_pgtables with mmap_lock write lock in exit_mmap Michal Hocko
2021-12-09 19:03 ` Suren Baghdasaryan
2021-12-10 9:20 ` Michal Hocko
2021-12-09 9:12 ` Michal Hocko [this message]
2021-12-09 16:24 ` [PATCH 4/3] mm: drop MMF_OOM_SKIP from exit_mmap Suren Baghdasaryan
2021-12-09 16:47 ` Michal Hocko
2021-12-09 17:06 ` Suren Baghdasaryan
2021-12-16 2:26 ` Suren Baghdasaryan
2021-12-16 11:49 ` Johannes Weiner
2021-12-16 17:23 ` Suren Baghdasaryan
2021-12-30 5:59 ` Suren Baghdasaryan
2021-12-30 8:24 ` Michal Hocko
2021-12-30 17:29 ` Suren Baghdasaryan
2022-01-03 12:11 ` Michal Hocko
2022-01-03 21:16 ` Hugh Dickins
2022-01-04 22:24 ` Suren Baghdasaryan
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