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Wed, 19 Feb 2020 01:44:49 +0000 (UTC) Received: by mail-pj1-f65.google.com with SMTP id q39so1821202pjc.0 for ; Tue, 18 Feb 2020 17:44:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=/6BKpu6I9GWZilmKCDR/xIEf9kb10U/fQ/hS1RFxo/E=; b=AeiF/BUIODJ7Elpdb3GXCCzXBoQS9IDbCw9VSMC/jL+pPhcr/hr375CchvyTPhz7Pw 0UOfnIko0AblDWL/yTdmeiTlRoIfhMWdWFD3hNHRiqveweEiIFdLmzsDjyssGqVlyrTi febRwSW0h0+kaMkhfKy6efdR7uMe5zL+d+KmyIKLPs0rgr5VxIwjrVpWWZEPFxsMwZ23 J/8duxiMxzzsojGZ4V6XQhchtynRJdtbiMasGQl4+ZCJDiom8Qude7YarbGY5V0fKzVt AFoKRAVeNBBiW7zrGGHfvJ2A02+p1VpXuF6g0cnYJV37hKbKe7v2cv28gZItVOFqnAa3 aTPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=/6BKpu6I9GWZilmKCDR/xIEf9kb10U/fQ/hS1RFxo/E=; 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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 f6d9b9e66243..c55a18fe71f9 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, str= uct mm_struct *mm, if (write) { if (down_write_killable(&mm->mmap_sem)) return -EINTR; + if (current->mm !=3D mm && !mmget_still_valid(mm)) + goto skip_mm; } else { down_read(&mm->mmap_sem); } @@ -1169,6 +1171,7 @@ int do_madvise(struct task_struct *target_task, str= uct mm_struct *mm, } out: blk_finish_plug(&plug); +skip_mm: if (write) up_write(&mm->mmap_sem); else --=20 2.25.0.265.gbab2e86ba0-goog