From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <darrick.wong@oracle.com>,
linux-xfs@vger.kernel.org, jlayton@kernel.org
Subject: Re: [PATCH] xfs: Do not free xfs_extent_busy from inside a spinlock
Date: Tue, 23 Jul 2019 08:51:35 -0700 [thread overview]
Message-ID: <20190723155135.GA16481@infradead.org> (raw)
In-Reply-To: <20190723153133.wqt3p3dqaghxbkpr@orion.maiolino.org>
On Tue, Jul 23, 2019 at 05:31:33PM +0200, Carlos Maiolino wrote:
> CC'ing Jeff so he can maybe chime in too.
>
>
> > Er, what problem does this solve? Does holding on to the pag spinlock
> > too long while memory freeing causes everything else to stall? When is
> > memory freeing slow enough to cause a noticeable impact?
>
> Jeff detected it when using this patch:
>
> https://marc.info/?l=linux-mm&m=156388753722881&w=2
>
> At first I don't see any specific problem, but I don't think we are supposed to
> use kmem_free() inside interrupt context anyway. So, even though there is no
> visible side effect, it should be fixed IMHO. With the patch above, the side
> effect is a bunch of warnings :P
This is going to break lots of places in xfs. While we have separate
allocation side wrappers for plain kmalloc vs using a vmalloc fallback we
always use the same free side wrapper. We could fix this by adding a
kmem_free_large and switch all places that allocated using
kmem_alloc_large to that, but it will require a bit of work.
next prev parent reply other threads:[~2019-07-23 15:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-23 15:00 [PATCH] xfs: Do not free xfs_extent_busy from inside a spinlock Carlos Maiolino
2019-07-23 15:11 ` Darrick J. Wong
2019-07-23 15:31 ` Carlos Maiolino
2019-07-23 15:51 ` Christoph Hellwig [this message]
2019-07-23 17:07 ` Jeff Layton
2019-07-23 17:08 ` Christoph Hellwig
2019-07-23 17:38 ` Jeff Layton
2019-07-23 17:41 ` Christoph Hellwig
2019-07-23 15:13 ` Carlos Maiolino
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