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Date:   Mon, 29 Jun 2020 16:45:14 +0300
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Subject: Re: [PATCH 6/6] mm: Add memalloc_nowait
To:     Michal Hocko <mhocko@kernel.org>,
        Matthew Wilcox <willy@infradead.org>
CC:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-xfs@vger.kernel.org, dm-devel@redhat.com,
        Mikulas Patocka <mpatocka@redhat.com>,
        Jens Axboe <axboe@kernel.dk>, NeilBrown <neilb@suse.de>
From:   Mike Rapoport <rppt@kernel.org>
Message-ID: <6421BC93-CF2F-4697-B5CB-5ECDAA9FCB37@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
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On June 29, 2020 3:52:31 PM GMT+03:00, Michal Hocko <mhocko@kernel=2Eorg> =
wrote:
>On Mon 29-06-20 13:18:16, Matthew Wilcox wrote:
>> On Mon, Jun 29, 2020 at 08:08:51AM +0300, Mike Rapoport wrote:
>> > > @@ -886,8 +868,12 @@ static struct dm_buffer
>*__alloc_buffer_wait_no_callback(struct dm_bufio_client
>> > >  			return NULL;
>> > > =20
>> > >  		if (dm_bufio_cache_size_latch !=3D 1 && !tried_noio_alloc) {
>> > > +			unsigned noio_flag;
>> > > +
>> > >  			dm_bufio_unlock(c);
>> > > -			b =3D alloc_buffer(c, GFP_NOIO | __GFP_NORETRY |
>__GFP_NOMEMALLOC | __GFP_NOWARN);
>> > > +			noio_flag =3D memalloc_noio_save();
>> >=20
>> > I've read the series twice and I'm still missing the definition of
>> > memalloc_noio_save()=2E
>> >=20
>> > And also it would be nice to have a paragraph about it in
>> > Documentation/core-api/memory-allocation=2Erst
>>=20
>>
>Documentation/core-api/gfp_mask-from-fs-io=2Erst:``memalloc_nofs_save``,
>``memalloc_nofs_restore`` respectively ``memalloc_noio_save``,
>> Documentation/core-api/gfp_mask-from-fs-io=2Erst:   :functions:
>memalloc_noio_save memalloc_noio_restore
>> Documentation/core-api/gfp_mask-from-fs-io=2Erst:allows nesting so it
>is safe to call ``memalloc_noio_save`` or
>=20
>The patch is adding memalloc_nowait* and I suspect Mike had that in
>mind, which would be a fair request=2E=20

Right, sorry misprinted that=2E

> Btw=2E we are missing
>memalloc_nocma*
>documentation either - I was just reminded of its existence today=2E=2E
--=20
Sincerely yours,
Mike