linux-kernel - [PATCH 4.17 36/67] fs/proc/task_mmu.c: fix Locked field in /proc/pid/smaps*

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Date:   Mon, 16 Jul 2018 09:35:05 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>,
        Thomas Lindroth <thomas.lindroth@...il.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Daniel Colascione <dancol@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.17 36/67] fs/proc/task_mmu.c: fix Locked field in /proc/pid/smaps*

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vlastimil Babka <vbabka@...e.cz>

commit e70cc2bd579e8a9d6d153762f0fe294d0e652ff0 upstream.

Thomas reports:
 "While looking around in /proc on my v4.14.52 system I noticed that all
  processes got a lot of "Locked" memory in /proc/*/smaps. A lot more
  memory than a regular user can usually lock with mlock().

  Commit 493b0e9d945f (in v4.14-rc1) seems to have changed the behavior
  of "Locked".

  Before that commit the code was like this. Notice the VM_LOCKED check.

           (vma->vm_flags & VM_LOCKED) ?
                (unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);

  After that commit Locked is now the same as Pss:

	  (unsigned long)(mss->pss >> (10 + PSS_SHIFT)));

  This looks like a mistake."

Indeed, the commit has added mss->pss_locked with the correct value that
depends on VM_LOCKED, but forgot to actually use it.  Fix it.

Link: http://lkml.kernel.org/r/ebf6c7fb-fec3-6a26-544f-710ed193c154@suse.cz
Fixes: 493b0e9d945f ("mm: add /proc/pid/smaps_rollup")
Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Reported-by: Thomas Lindroth <thomas.lindroth@...il.com>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Cc: Daniel Colascione <dancol@...gle.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/proc/task_mmu.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -831,7 +831,8 @@ static int show_smap(struct seq_file *m,
 		SEQ_PUT_DEC(" kB\nSwap:           ", mss->swap);
 		SEQ_PUT_DEC(" kB\nSwapPss:        ",
 						mss->swap_pss >> PSS_SHIFT);
-		SEQ_PUT_DEC(" kB\nLocked:         ", mss->pss >> PSS_SHIFT);
+		SEQ_PUT_DEC(" kB\nLocked:         ",
+						mss->pss_locked >> PSS_SHIFT);
 		seq_puts(m, " kB\n");
 	}
 	if (!rollup_mode) {