From mboxrd@z Thu Jan 1 00:00:00 1970 From: Minchan Kim Subject: [PATCH v2 3/5] mm/madvise: employ mmget_still_valid for write lock Date: Thu, 16 Jan 2020 15:59:51 -0800 Message-ID: <20200116235953.163318-4-minchan@kernel.org> References: <20200116235953.163318-1-minchan@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200116235953.163318-1-minchan@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: LKML , linux-mm , linux-api@vger.kernel.org, oleksandr@redhat.com, Suren Baghdasaryan , Tim Murray , Daniel Colascione , Sandeep Patil , Sonny Rao , Brian Geffon , Michal Hocko , Johannes Weiner , Shakeel Butt , John Dias , ktkhai@virtuozzo.com, christian.brauner@ubuntu.com, sjpark@amazon.de, Minchan Kim , Minchan Kim List-Id: linux-api@vger.kernel.org From: Oleksandr Natalenko 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 Signed-off-by: Minchan Kim --- mm/madvise.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/madvise.c b/mm/madvise.c index 59b5cc99ef61..84cffd0900f1 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1059,6 +1059,8 @@ 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); } @@ -1109,6 +1111,7 @@ 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.rc1.283.g88dfdc4193-goog