From: Dennis Zhou <dennis@kernel.org>
To: Wang Yugui <wangyugui@e16-tech.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, linux-btrfs@vger.kernel.org
Subject: Re: unexpected -ENOMEM from percpu_counter_init()
Date: Thu, 8 Apr 2021 02:44:38 +0000 [thread overview]
Message-ID: <YG5uFrWpwDHMhdR1@google.com> (raw)
In-Reply-To: <20210408072800.6C1F.409509F4@e16-tech.com>
On Thu, Apr 08, 2021 at 07:28:01AM +0800, Wang Yugui wrote:
> Hi,
>
> > > > > upper caller:
> > > > > nofs_flag = memalloc_nofs_save();
> > > > > ret = btrfs_drew_lock_init(&root->snapshot_lock);
> > > > > memalloc_nofs_restore(nofs_flag);
> >
> > The issue is here. nofs is set which means percpu attempts an atomic
> > allocation. If it cannot find anything already allocated it isn't happy.
> > This was done before memalloc_nofs_{save/restore}() were pervasive.
> >
> > Percpu should probably try to allocate some pages if possible even if
> > nofs is set.
>
> Thanks.
>
> I will wait for the patch, and then test it.
>
I'm currently a bit busy with some other things. Adding support I don't
think will be much work, just a little bit tricky.
I recommend carrying what you have minus the change to reserved percpu
memory for now. If I'm the one to write it, I'll cc you.
Thanks,
Dennis
next prev parent reply other threads:[~2021-04-08 2:44 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 10:51 unexpected -ENOMEM from percpu_counter_init() Wang Yugui
2021-04-02 1:49 ` Wang Yugui
2021-04-07 12:35 ` Vlastimil Babka
2021-04-07 13:09 ` Wang Yugui
2021-04-07 14:56 ` Dennis Zhou
2021-04-07 23:28 ` Wang Yugui
2021-04-08 2:44 ` Dennis Zhou [this message]
2021-04-08 9:20 ` Wang Yugui
2021-04-08 13:48 ` Dennis Zhou
2021-04-08 14:28 ` Filipe Manana
2021-04-08 15:02 ` Dennis Zhou
2021-04-09 11:39 ` Filipe Manana
2021-04-09 13:39 ` Dennis Zhou
2021-04-09 13:42 ` Filipe Manana
2021-04-09 0:08 ` Wang Yugui
2021-04-09 2:14 ` Dennis Zhou
2021-04-09 4:02 ` Wang Yugui
2021-04-09 7:36 ` Wang Yugui
2021-04-09 7:48 ` Wang Yugui
2021-04-09 13:56 ` Dennis Zhou
2021-04-10 15:29 ` Wang Yugui
2021-04-10 15:52 ` Dennis Zhou
2021-04-10 16:08 ` Wang Yugui
2021-04-11 15:20 ` Wang Yugui
2021-04-12 4:03 ` Dennis Zhou
2021-04-12 5:24 ` Wang Yugui
2021-04-09 9:52 ` Wang Yugui
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