From: Omar Sandoval <osandov@osandov.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: kernel test robot <xiaolong.ye@intel.com>,
Vinnie Magro <vmagro@fb.com>, David Sterba <dsterba@suse.com>,
Omar Sandoval <osandov@fb.com>,
LKML <linux-kernel@vger.kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
lkp@01.org
Subject: Re: [lkp-robot] [btrfs] beeeccca9b: WARNING:at_mm/util.c:#kvmalloc_node
Date: Wed, 31 May 2017 02:12:02 -0700 [thread overview]
Message-ID: <20170531091202.GA769@vader> (raw)
In-Reply-To: <20170531065128.GB3853@dhcp22.suse.cz>
On Wed, May 31, 2017 at 08:51:28AM +0200, Michal Hocko wrote:
> On Wed 31-05-17 14:30:33, kernel test robot wrote:
> >
> > FYI, we noticed the following commit:
> >
> > commit: beeeccca9bebcec386cc31c250cff8a06cf27034 ("btrfs: Use kvzalloc instead of kzalloc/vmalloc in alloc_bitmap")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> I have intentionally skipped alloc_bitmap because it relies on GFP_NOFS.
> This doesn't work properly when falling back to vmalloc and that is what
> the warning reported here says. I believe the right approach is to check
> whether the GFP_NOFS is _really_ needed and document why if yes.
> Otherwise drop the NOFS part in one patch with the explanation and
> convert it to kvmalloc in a separate patch.
Unfortunately we really do need GFP_NOFS here, the free space tree is
modified while we are committing a fs transaction, sometimes in the
critical section when we block new operations from joining the
transaction. Looking at the comment in kvmalloc_node():
/*
* vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
* so the given set of flags has to be compatible.
*/
WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
has alloc_bitmap() always been broken by virtue of calling vmalloc()
with GFP_NOFS?
WARNING: multiple messages have this Message-ID (diff)
From: Omar Sandoval <osandov@osandov.com>
To: lkp@lists.01.org
Subject: Re: [lkp-robot] [btrfs] beeeccca9b: WARNING:at_mm/util.c:#kvmalloc_node
Date: Wed, 31 May 2017 02:12:02 -0700 [thread overview]
Message-ID: <20170531091202.GA769@vader> (raw)
In-Reply-To: <20170531065128.GB3853@dhcp22.suse.cz>
[-- Attachment #1: Type: text/plain, Size: 1333 bytes --]
On Wed, May 31, 2017 at 08:51:28AM +0200, Michal Hocko wrote:
> On Wed 31-05-17 14:30:33, kernel test robot wrote:
> >
> > FYI, we noticed the following commit:
> >
> > commit: beeeccca9bebcec386cc31c250cff8a06cf27034 ("btrfs: Use kvzalloc instead of kzalloc/vmalloc in alloc_bitmap")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> I have intentionally skipped alloc_bitmap because it relies on GFP_NOFS.
> This doesn't work properly when falling back to vmalloc and that is what
> the warning reported here says. I believe the right approach is to check
> whether the GFP_NOFS is _really_ needed and document why if yes.
> Otherwise drop the NOFS part in one patch with the explanation and
> convert it to kvmalloc in a separate patch.
Unfortunately we really do need GFP_NOFS here, the free space tree is
modified while we are committing a fs transaction, sometimes in the
critical section when we block new operations from joining the
transaction. Looking at the comment in kvmalloc_node():
/*
* vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
* so the given set of flags has to be compatible.
*/
WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
has alloc_bitmap() always been broken by virtue of calling vmalloc()
with GFP_NOFS?
next prev parent reply other threads:[~2017-05-31 9:12 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-31 6:30 [lkp-robot] [btrfs] beeeccca9b: WARNING:at_mm/util.c:#kvmalloc_node kernel test robot
2017-05-31 6:30 ` kernel test robot
2017-05-31 6:51 ` Michal Hocko
2017-05-31 6:51 ` Michal Hocko
2017-05-31 9:12 ` Omar Sandoval [this message]
2017-05-31 9:12 ` Omar Sandoval
2017-05-31 9:19 ` Michal Hocko
2017-05-31 9:19 ` Michal Hocko
2017-05-31 9:29 ` Omar Sandoval
2017-05-31 9:29 ` Omar Sandoval
2017-05-31 10:30 ` Michal Hocko
2017-05-31 10:30 ` Michal Hocko
2017-05-31 14:58 ` David Sterba
2017-05-31 14:58 ` David Sterba
2017-06-05 3:30 ` Stephen Rothwell
2017-06-05 3:30 ` Stephen Rothwell
2017-06-05 11:43 ` David Sterba
2017-06-05 11:43 ` David Sterba
2017-06-05 12:11 ` Stephen Rothwell
2017-06-05 12:11 ` Stephen Rothwell
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