From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>,
Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Cc: io-uring <io-uring@vger.kernel.org>
Subject: Re: [PATCH 1/1] io_uring: use proper references for fallback_req locking
Date: Mon, 4 May 2020 10:12:07 -0600 [thread overview]
Message-ID: <84554b60-2ec5-9876-79ce-5962ae5580e4@kernel.dk> (raw)
In-Reply-To: <07fda8ac-93e4-e488-0575-026b339d2c36@gmail.com>
On 5/3/20 6:52 AM, Pavel Begunkov wrote:
> On 30/04/2020 17:52, Jens Axboe wrote:
>> On 4/29/20 6:47 PM, Bijan Mottahedeh wrote:
>>> Use ctx->fallback_req address for test_and_set_bit_lock() and
>>> clear_bit_unlock().
>>
>> Thanks, applied.
>>
>
> How about getting rid of it? As once was fairly noticed, we're screwed in many
> other ways in case of OOM. Otherwise we at least need to make async context
> allocation more resilient.
Not sure how best to handle it, it really sucks to have things fall apart
under high memory pressure, a condition that isn't that rare in production
systems. But as you say, it's only a half measure currently. We could have
the fallback request have req->io already allocated, though. That would
provide what we need for guaranteed forward progress, even in the presence
of OOM conditions.
--
Jens Axboe
next prev parent reply other threads:[~2020-05-04 16:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1588207670-65832-1-git-send-email-bijan.mottahedeh@oracle.com>
[not found] ` <05997981-047c-a87b-c875-6ea7b229f586@kernel.dk>
2020-05-03 12:52 ` [PATCH 1/1] io_uring: use proper references for fallback_req locking Pavel Begunkov
2020-05-04 16:12 ` Jens Axboe [this message]
2020-05-04 16:28 ` Pavel Begunkov
2020-05-04 19:16 ` Bijan Mottahedeh
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=84554b60-2ec5-9876-79ce-5962ae5580e4@kernel.dk \
--to=axboe@kernel.dk \
--cc=asml.silence@gmail.com \
--cc=bijan.mottahedeh@oracle.com \
--cc=io-uring@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).