Re: Possible 6.5 regression: Huge values for "commited memory"

From: Helge Deller
Date: Sun Sep 17 2023 - 01:04:20 EST


Greg & Sasha,

can you please queue-up this upstream patch for kernel v6.5-stable ?

commit 3cec50490969afd4a76ccee441f747d869ccff77
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Sat Sep 16 12:31:42 2023 -0700

vm: fix move_vma() memory accounting being off

Thanks,
Helge


On 9/16/23 23:17, Linus Torvalds wrote:
On Sat, 16 Sept 2023 at 12:31, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

Does the attached patch fix the problem?

So while I didn't confirm the fix myself, I'm pretty sure that was it.
Getting the return value wrong would cause an incorrect extra
vm_acct_memory() call in the non-error case when VM_ACCOUNT is set
(and mean the loss of one in the error case, but the error case never
happens in practice).

Which then causes 'vm_committed_as' to grow when it shouldn't, and
causes exactly that "Committed_AS" in /proc/meminfo to be off.

So here's the same patch, but now with a proper commit message etc.

I haven't pushed it out (because it would be lovely to get a
"Tested-by" for it, and that will make the commit ID change), but I'll
probably do so later today, with or without confirmation, because it
does seem to be the problem.

Linus