Messages in this thread Patch in this message | | | From | Minchan Kim <> | Subject | [PATCH v4 5/8] mm/madvise: employ mmget_still_valid for write lock | Date | Wed, 12 Feb 2020 15:39:43 -0800 |
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From: Oleksandr Natalenko <oleksandr@redhat.com>
Do the very same trick as we already do since 04f5866e41fb. KSM hints will require locking mmap_sem for write since they modify vm_flags, so for remote KSM hinting this additional check is needed.
Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com> Signed-off-by: Minchan Kim <minchan@kernel.org> --- mm/madvise.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/madvise.c b/mm/madvise.c index 276b9d81c1dd..71f0ba199ae8 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1120,6 +1120,8 @@ int do_madvise(struct task_struct *task, unsigned long start, if (write) { if (down_write_killable(&mm->mmap_sem)) return -EINTR; + if (current->mm != mm && !mmget_still_valid(mm)) + goto skip_mm; } else { down_read(&mm->mmap_sem); } @@ -1170,6 +1172,7 @@ int do_madvise(struct task_struct *task, unsigned long start, } out: blk_finish_plug(&plug); +skip_mm: if (write) up_write(&mm->mmap_sem); else -- 2.25.0.225.g125e21ebc7-goog
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