From: Luis Henriques <lhenriques@suse.com>
To: Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennisszhou@gmail.com>,
Christoph Lameter <cl@linux.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] percpu: fix iteration to prevent skipping over block
Date: Thu, 28 Sep 2017 09:31:00 +0100 [thread overview]
Message-ID: <87lgkzkywr.fsf@hermes> (raw)
In-Reply-To: <20170927215125.GB15129@devbig577.frc2.facebook.com> (Tejun Heo's message of "Wed, 27 Sep 2017 14:51:25 -0700")
Tejun Heo <tj@kernel.org> writes:
> On Wed, Sep 27, 2017 at 04:35:00PM -0500, Dennis Zhou wrote:
>> The iterator functions pcpu_next_md_free_region and
>> pcpu_next_fit_region use the block offset to determine if they have
>> checked the area in the prior iteration. However, this causes an issue
>> when the block offset is greater than subsequent block contig hints. If
>> within the iterator it moves to check subsequent blocks, it may fail in
>> the second predicate due to the block offset not being cleared. Thus,
>> this causes the allocator to skip over blocks leading to false failures
>> when allocating from the reserved chunk. While this happens in the
>> general case as well, it will only fail if it cannot allocate a new
>> chunk.
>>
>> This patch resets the block offset to 0 to pass the second predicate
>> when checking subseqent blocks within the iterator function.
>>
>> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
>> Reported-by: Luis Henriques <lhenriques@suse.com>
>
> Luis, can you please verify that this fixes the allocaiton failure you
> were seeing?
I can confirm that I'm no longer seeing the allocation failure after
applying these patches. Feel free to add my:
Tested-by: Luis Henriques <lhenriques@suse.com>
Cheers,
--
Luis
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-09-28 8:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 21:34 [PATCH 0/2] percpu: fix block iterators and reserved chunk stats Dennis Zhou
2017-09-27 21:34 ` [PATCH 1/2] percpu: fix starting offset for chunk statistics traversal Dennis Zhou
2017-09-27 21:46 ` Tejun Heo
2017-09-27 21:35 ` [PATCH 2/2] percpu: fix iteration to prevent skipping over block Dennis Zhou
2017-09-27 21:51 ` Tejun Heo
2017-09-28 8:31 ` Luis Henriques [this message]
2017-09-28 14:40 ` Tejun Heo
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=87lgkzkywr.fsf@hermes \
--to=lhenriques@suse.com \
--cc=cl@linux.com \
--cc=dennisszhou@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=tj@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).