From: Christopher Lameter <cl@linux.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Ming Lei <ming.lei@redhat.com>,
Dave Chinner <david@fromorbit.com>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Christoph Hellwig <hch@lst.de>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org,
James Bottomley <James.Bottomley@hansenpartnership.com>,
linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two)
Date: Fri, 30 Aug 2019 17:41:46 +0000 [thread overview]
Message-ID: <0100016ce39e6bb9-ad20e033-f3f4-4e6d-85d6-87e7d07823ae-000000@email.amazonses.com> (raw)
In-Reply-To: <20190829073921.GA21880@dhcp22.suse.cz>
On Thu, 29 Aug 2019, Michal Hocko wrote:
> > There are many places in the kernel which assume alignment. They break
> > when it's not supplied. I believe we have a better overall system if
> > the MM developers provide stronger guarantees than the MM consumers have
> > to work around only weak guarantees.
>
> I absolutely agree. A hypothetical benefit of a new implementation
> doesn't outweigh the complexity the existing code has to jump over or
> worse is not aware of and it is broken silently. My general experience
> is that the later is more likely with a large variety of drivers we have
> in the tree and odd things they do in general.
The current behavior without special alignment for these caches has been
in the wild for over a decade. And this is now coming up?
There is one case now it seems with a broken hardware that has issues and
we now move to an alignment requirement from the slabs with exceptions and
this and that?
If there is an exceptional alignment requirement then that needs to be
communicated to the allocator. A special flag or create a special
kmem_cache or something.
next prev parent reply other threads:[~2019-08-30 17:41 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 11:16 [PATCH v2 0/2] guarantee natural alignment for kmalloc() Vlastimil Babka
2019-08-26 11:16 ` [PATCH v2 1/2] mm, sl[ou]b: improve memory accounting Vlastimil Babka
2019-08-26 11:16 ` [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two) Vlastimil Babka
2019-08-28 18:45 ` Christopher Lameter
2019-08-28 19:46 ` Matthew Wilcox
2019-08-28 22:24 ` Dave Chinner
2019-08-29 7:56 ` Vlastimil Babka
2019-08-30 0:29 ` Dave Chinner
2019-08-29 7:39 ` Michal Hocko
2019-08-30 17:41 ` Christopher Lameter [this message]
2019-09-01 0:52 ` Matthew Wilcox
2019-09-03 20:13 ` Christopher Lameter
2019-09-03 20:53 ` Matthew Wilcox
2019-09-04 5:19 ` Christoph Hellwig
2019-09-04 6:40 ` Ming Lei
2019-09-04 7:20 ` Vlastimil Babka
2019-09-04 19:31 ` Christopher Lameter
2019-09-23 16:36 ` Vlastimil Babka
2019-09-23 17:17 ` David Sterba
2019-09-23 17:51 ` Darrick J. Wong
2019-09-24 20:47 ` cl
2019-09-24 20:51 ` Matthew Wilcox
2019-09-24 20:55 ` cl
2019-09-26 13:02 ` David Sterba
2019-09-24 21:19 ` Vlastimil Babka
2019-09-24 21:53 ` Dave Chinner
2019-09-24 22:21 ` Darrick J. Wong
2019-09-24 20:52 ` cl
2019-09-24 23:54 ` Andrew Morton
2019-09-25 7:17 ` Vlastimil Babka
2019-09-26 0:16 ` Christopher Lameter
2019-09-26 0:14 ` Christopher Lameter
2019-09-26 7:41 ` Vlastimil Babka
2019-09-28 1:12 ` Christopher Lameter
2019-09-30 13:32 ` Matthew Wilcox
2019-09-23 17:54 ` Roman Gushchin
2019-09-30 8:06 ` Christoph Hellwig
2019-09-30 9:23 ` Michal Hocko
2019-09-30 9:32 ` Kirill A. Shutemov
2019-09-23 18:57 ` Matthew Wilcox
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