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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sat, 16 Sep 2023 14:17:09 -0700
Message-ID: <CAHk-=wjrEjaUw3oFVEYpF=AWAwrSM3sQTQHuPfFjFdQsvQxHeg@mail.gmail.com>
Subject: Re: Possible 6.5 regression: Huge values for "commited memory"
To:     Bagas Sanjaya <bagasdotme@gmail.com>,
        Michael Labiuk <michael.labiuk@virtuozzo.com>,
        Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Cc:     Linux PARISC <linux-parisc@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Regressions <regressions@lists.linux.dev>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>
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On Sat, 16 Sept 2023 at 12:31, Linus Torvalds
<torvalds@linux-foundation.org> 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

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