[PATCH v3 3/5] mm/madvise: employ mmget_still_valid for write lock
From: Minchan Kim <minchan@kernel.org>
Date: 2020-01-28 00:17:04
Also in:
linux-mm, lkml
Subsystem:
memory management, memory mapping - madvise (memory advice), the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, David Hildenbrand, Linus Torvalds
From: Oleksandr Natalenko <redacted> 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 <redacted> 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 00ffa7e92f79..bc0a72dbf80e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c@@ -1061,6 +1061,8 @@ static int madvise_common(struct task_struct *task, struct mm_struct *mm, 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); }
@@ -1111,6 +1113,7 @@ static int madvise_common(struct task_struct *task, struct mm_struct *mm, } out: blk_finish_plug(&plug); +skip_mm: if (write) up_write(&mm->mmap_sem); else
--
2.25.0.341.g760bfbb309-goog