From: Andres Freund <andres@anarazel.de>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>,
io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Memory uninitialized after "io_uring: keep table of pointers to ubufs"
Date: Thu, 3 Jun 2021 11:06:12 -0700 [thread overview]
Message-ID: <20210603180612.uchkn5qqa3j7rpgd@alap3.anarazel.de> (raw)
In-Reply-To: <d2c5b250-5a0f-5de5-061f-38257216389d@gmail.com>
Hi,
On 2021-05-29 12:03:12 +0100, Pavel Begunkov wrote:
> On 5/29/21 1:33 AM, Andres Freund wrote:
> > Hi,
> >
> > I started to see buffer registration randomly failing with ENOMEM on
> > 5.13. Registering buffer or two often succeeds, but more than that
> > rarely. Running the same program as root succeeds - but the user has a high
> > rlimit.
> >
> > The issue is that io_sqe_buffer_register() doesn't initialize
> > imu. io_buffer_account_pin() does imu->acct_pages++, before calling
> > io_account_mem(ctx, imu->acct_pages);
> >
> > Which means that a random amount of memory is being accounted for. On the first
> > few allocations this sometimes fails to fail because the memory is zero, but
> > after a bit of reuse...
>
> Makes sense, thanks for digging in. I've just sent a patch, would
> be great if you can test it or send your own.
Sorry for the slow response, I'm off this week. I did just get around to
test and unsurprisingly: The patch does fix the issue.
Greetings,
Andres Freund
next prev parent reply other threads:[~2021-06-03 18:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-29 0:33 Memory uninitialized after "io_uring: keep table of pointers to ubufs" Andres Freund
2021-05-29 11:03 ` Pavel Begunkov
2021-06-03 18:06 ` Andres Freund [this message]
2021-06-03 18:13 ` Jens Axboe
2021-06-04 14:16 ` Pavel Begunkov
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