From: Andrew Morton <akpm@linux-foundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Roman Gushchin <guroan@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Johannes Weiner <hannes@cmpxchg.org>,
Vlastimil Babka <vbabka@suse.cz>, Roman Gushchin <guro@fb.com>,
Christoph Hellwig <hch@lst.de>,
Joel Fernandes <joelaf@google.com>
Subject: Re: [PATCH v4 1/2] mm: refactor __vunmap() to avoid duplicated call to find_vm_area()
Date: Thu, 18 Apr 2019 15:24:31 -0700 [thread overview]
Message-ID: <20190418152431.c583ef892a8028c662db3e6a@linux-foundation.org> (raw)
In-Reply-To: <20190418111834.GE7751@bombadil.infradead.org>
On Thu, 18 Apr 2019 04:18:34 -0700 Matthew Wilcox <willy@infradead.org> wrote:
> On Wed, Apr 17, 2019 at 02:58:27PM -0700, Andrew Morton wrote:
> > On Wed, 17 Apr 2019 12:40:01 -0700 Roman Gushchin <guroan@gmail.com> wrote:
> > > +static struct vm_struct *__remove_vm_area(struct vmap_area *va)
> > > +{
> > > + struct vm_struct *vm = va->vm;
> > > +
> > > + might_sleep();
> >
> > Where might __remove_vm_area() sleep?
> >
> > >From a quick scan I'm only seeing vfree(), and that has the
> > might_sleep_if(!in_interrupt()).
> >
> > So perhaps we can remove this...
>
> See commit 5803ed292e63 ("mm: mark all calls into the vmalloc subsystem as potentially sleeping")
>
> It looks like the intent is to unconditionally check might_sleep() at
> the entry points to the vmalloc code, rather than only catch them in
> the occasional place where it happens to go wrong.
afaict, vfree() will only do a mutex_trylock() in
try_purge_vmap_area_lazy(). So does vfree actually sleep in any
situation? Whether or not local interrupts are enabled?
next prev parent reply other threads:[~2019-04-18 22:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 19:40 [PATCH v4 0/2] vmalloc enhancements Roman Gushchin
2019-04-17 19:40 ` [PATCH v4 1/2] mm: refactor __vunmap() to avoid duplicated call to find_vm_area() Roman Gushchin
2019-04-17 21:58 ` Andrew Morton
2019-04-17 23:02 ` Roman Gushchin
2019-04-18 11:18 ` Matthew Wilcox
2019-04-18 22:24 ` Andrew Morton [this message]
2019-04-18 23:17 ` Eric Dumazet
2019-04-19 19:08 ` Al Viro
2019-04-17 19:40 ` [PATCH v4 2/2] mm: show number of vmalloc pages in /proc/meminfo Roman Gushchin
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