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From: Michal Hocko <mhocko@kernel.org>
To: kernel test robot <xiaolong.ye@intel.com>
Cc: 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 08:51:28 +0200	[thread overview]
Message-ID: <20170531065128.GB3853@dhcp22.suse.cz> (raw)
In-Reply-To: <20170531063033.GC1795@yexl-desktop>

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.

-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: lkp@lists.01.org
Subject: Re: [lkp-robot] [btrfs] beeeccca9b: WARNING:at_mm/util.c:#kvmalloc_node
Date: Wed, 31 May 2017 08:51:28 +0200	[thread overview]
Message-ID: <20170531065128.GB3853@dhcp22.suse.cz> (raw)
In-Reply-To: <20170531063033.GC1795@yexl-desktop>

[-- Attachment #1: Type: text/plain, Size: 730 bytes --]

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.

-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2017-05-31  6:51 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 [this message]
2017-05-31  6:51   ` Michal Hocko
2017-05-31  9:12   ` Omar Sandoval
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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