From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>,
linux-xfs@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
penguin-kernel@I-love.SAKURA.ne.jp
Subject: Re: [PATCH 2/3] xfs: add kmem_alloc_io()
Date: Thu, 22 Aug 2019 10:51:30 +0200 [thread overview]
Message-ID: <20190822085130.GI2349@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190822075948.GA31346@infradead.org>
On Thu, Aug 22, 2019 at 12:59:48AM -0700, Christoph Hellwig wrote:
> On Thu, Aug 22, 2019 at 10:31:32AM +1000, Dave Chinner wrote:
> > > Btw, I think we should eventually kill off KM_NOFS and just use
> > > PF_MEMALLOC_NOFS in XFS, as the interface makes so much more sense.
> > > But that's something for the future.
> >
> > Yeah, and it's not quite as simple as just using PF_MEMALLOC_NOFS
> > at high levels - we'll still need to annotate callers that use KM_NOFS
> > to avoid lockdep false positives. i.e. any code that can be called from
> > GFP_KERNEL and reclaim context will throw false positives from
> > lockdep if we don't annotate tehm correctly....
>
> Oh well. For now we have the XFS kmem_wrappers to turn that into
> GFP_NOFS so we shouldn't be too worried, but I think that is something
> we should fix in lockdep to ensure it is generally useful. I've added
> the maintainers and relevant lists to kick off a discussion.
Strictly speaking the fs_reclaim annotation is no longer part of the
lockdep core, but is simply a fake lock in page_alloc.c and thus falls
under the mm people's purview.
That said; it should be fairly straight forward to teach
__need_fs_reclaim() about PF_MEMALLOC_NOFS, much like how it already
knows about PF_MEMALLOC.
next prev parent reply other threads:[~2019-08-22 8:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190821083820.11725-1-david@fromorbit.com>
[not found] ` <20190821083820.11725-3-david@fromorbit.com>
[not found] ` <20190821232440.GB24904@infradead.org>
[not found] ` <20190822003131.GR1119@dread.disaster.area>
2019-08-22 7:59 ` [PATCH 2/3] xfs: add kmem_alloc_io() Christoph Hellwig
2019-08-22 8:51 ` Peter Zijlstra [this message]
2019-08-22 9:10 ` Peter Zijlstra
2019-08-22 10:14 ` Dave Chinner
2019-08-22 11:14 ` Vlastimil Babka
2019-08-22 12:07 ` Dave Chinner
2019-08-22 12:19 ` Vlastimil Babka
2019-08-22 13:17 ` Dave Chinner
2019-08-22 14:26 ` Vlastimil Babka
2019-08-26 12:21 ` Michal Hocko
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