lkml.org 
[lkml]   [2016]   [Aug]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/4] mm: mlock: avoid increase mm->locked_vm on mlock() when already mlock2(,MLOCK_ONFAULT)
On Tue, Aug 30, 2016 at 06:59:39PM +0800, wei.guo.simon@gmail.com wrote:
> From: Simon Guo <wei.guo.simon@gmail.com>
>
> When one vma was with flag VM_LOCKED|VM_LOCKONFAULT (by invoking
> mlock2(,MLOCK_ONFAULT)), it can again be populated with mlock() with
> VM_LOCKED flag only.
>
> There is a hole in mlock_fixup() which increase mm->locked_vm twice even
> the two operations are on the same vma and both with VM_LOCKED flags.
>
> The issue can be reproduced by following code:
> mlock2(p, 1024 * 64, MLOCK_ONFAULT); //VM_LOCKED|VM_LOCKONFAULT
> mlock(p, 1024 * 64); //VM_LOCKED
> Then check the increase VmLck field in /proc/pid/status(to 128k).
>
> When vma is set with different vm_flags, and the new vm_flags is with
> VM_LOCKED, it is not necessarily be a "new locked" vma. This patch
> corrects this bug by prevent mm->locked_vm from increment when old
> vm_flags is already VM_LOCKED.
>
> Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

--
Kirill A. Shutemov

\
 
 \ /
  Last update: 2016-09-17 09:58    [W:0.075 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site