From: Andrew Morton <akpm@linux-foundation.org>
To: Michal Hocko <mhocko@suse.com>
Cc: Dave Chinner <david@fromorbit.com>, Neil Brown <neilb@suse.de>,
Christoph Hellwig <hch@lst.de>,
Uladzislau Rezki <urezki@gmail.com>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
LKML <linux-kernel@vger.kernel.org>,
Ilya Dryomov <idryomov@gmail.com>,
Jeff Layton <jlayton@kernel.org>
Subject: Re: [PATCH v2 2/4] mm/vmalloc: add support for __GFP_NOFAIL
Date: Sat, 27 Nov 2021 16:00:43 -0800 [thread overview]
Message-ID: <20211127160043.1512b4063f30b4d043b37420@linux-foundation.org> (raw)
In-Reply-To: <YaC7jij1hHtdOJdE@dhcp22.suse.cz>
On Fri, 26 Nov 2021 11:48:46 +0100 Michal Hocko <mhocko@suse.com> wrote:
> On Mon 22-11-21 16:32:31, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> >
> > Dave Chinner has mentioned that some of the xfs code would benefit from
> > kvmalloc support for __GFP_NOFAIL because they have allocations that
> > cannot fail and they do not fit into a single page.
> >
> > The large part of the vmalloc implementation already complies with the
> > given gfp flags so there is no work for those to be done. The area
> > and page table allocations are an exception to that. Implement a retry
> > loop for those.
> >
> > Add a short sleep before retrying. 1 jiffy is a completely random
> > timeout. Ideally the retry would wait for an explicit event - e.g.
> > a change to the vmalloc space change if the failure was caused by
> > the space fragmentation or depletion. But there are multiple different
> > reasons to retry and this could become much more complex. Keep the retry
> > simple for now and just sleep to prevent from hogging CPUs.
> >
> > Signed-off-by: Michal Hocko <mhocko@suse.com>
>
> Are there still any concerns around this patch or the approach in
> general?
Well. Like GFP_NOFAIL, every use is a sin. But I don't think I've
ever seen a real-world report of anyone hitting GFP_NOFAIL's
theoretical issues.
I assume there will be a v3?
next prev parent reply other threads:[~2021-11-28 0:02 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-22 15:32 [PATCH v2 0/4] extend vmalloc support for constrained allocations Michal Hocko
2021-11-22 15:32 ` [PATCH v2 1/4] mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc Michal Hocko
2021-11-23 19:05 ` Uladzislau Rezki
2021-11-26 15:13 ` Vlastimil Babka
2021-11-22 15:32 ` [PATCH v2 2/4] mm/vmalloc: add support for __GFP_NOFAIL Michal Hocko
2021-11-23 19:01 ` Uladzislau Rezki
2021-11-23 20:09 ` Michal Hocko
2021-11-24 20:46 ` Uladzislau Rezki
2021-11-24 1:02 ` Andrew Morton
2021-11-24 3:16 ` NeilBrown
2021-11-24 3:48 ` Andrew Morton
2021-11-24 5:23 ` NeilBrown
2021-11-25 0:32 ` Theodore Y. Ts'o
2021-11-26 14:50 ` Vlastimil Babka
2021-11-26 15:09 ` Michal Hocko
2021-11-24 23:45 ` Dave Chinner
2021-11-24 8:43 ` Michal Hocko
2021-11-24 20:37 ` Uladzislau Rezki
2021-11-25 8:48 ` Michal Hocko
2021-11-25 18:40 ` Uladzislau Rezki
2021-11-25 19:21 ` Michal Hocko
2021-11-24 20:11 ` Uladzislau Rezki
2021-11-25 8:46 ` Michal Hocko
2021-11-25 18:02 ` Uladzislau Rezki
2021-11-25 19:24 ` Michal Hocko
2021-11-25 20:03 ` Uladzislau Rezki
2021-11-25 20:13 ` Michal Hocko
2021-11-25 20:21 ` Uladzislau Rezki
2021-11-26 10:48 ` Michal Hocko
2021-11-28 0:00 ` Andrew Morton [this message]
2021-11-29 8:56 ` Michal Hocko
2021-11-26 15:32 ` Vlastimil Babka
2021-11-22 15:32 ` [PATCH v2 3/4] mm/vmalloc: be more explicit about supported gfp flags Michal Hocko
2021-11-23 18:58 ` Uladzislau Rezki
2021-11-26 15:39 ` Vlastimil Babka
2021-11-22 15:32 ` [PATCH v2 4/4] mm: allow !GFP_KERNEL allocations for kvmalloc Michal Hocko
2021-11-23 18:57 ` Uladzislau Rezki
2021-11-23 19:02 ` Uladzislau Rezki
2021-11-26 15:50 ` Vlastimil Babka
2021-11-24 22:55 ` [PATCH v2 0/4] extend vmalloc support for constrained allocations Dave Chinner
2021-11-25 8:58 ` Michal Hocko
2021-11-25 9:30 ` Michal Hocko
2021-11-25 21:30 ` Dave Chinner
2021-11-26 9:20 ` Vlastimil Babka
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