From: Michal Hocko <mhocko@suse.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, Barry Song <21cnbao@gmail.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
42.hyeyoo@gmail.com, cl@linux.com, iamjoonsoo.kim@lge.com,
lstoakes@gmail.com, penberg@kernel.org, rientjes@google.com,
roman.gushchin@linux.dev, urezki@gmail.com,
v-songbaohua@oppo.com, virtualization@lists.linux.dev,
hailong.liu@oppo.com, torvalds@linux-foundation.org
Subject: Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL
Date: Wed, 24 Jul 2024 15:31:42 +0200 [thread overview]
Message-ID: <ZqECPiU-3fJozzpB@tiehlicka> (raw)
In-Reply-To: <ZqEAUbtkIMCwVpgB@infradead.org>
On Wed 24-07-24 06:23:29, Christoph Hellwig wrote:
> On Wed, Jul 24, 2024 at 03:21:13PM +0200, Michal Hocko wrote:
> > Scope API is tricky here. Exactly because the scope itself could have
> > opportunistic GFP_NOWAIT allocations.
>
> Really, where? That just sounds f**cked up as callers using any kind
> of nofail API can be broken by a caller higher in the stack.
I do not see this a problem. There is no real reason to have a NOWAIT
allocation down the stack that has a different fallback strategy.
I am not saying that this is the current practice because I do not know
that but I am saying that this is not impossible to imagine and it makes
scoped NOFAIL context subtle and error prone.
> And that's totally independ of adding a NOFS/NOIO helper, so it'll need
> to be fixed.
>
> Adding more NOFS/NOIO wrappers while we're trying to kill the flag just
> is not helpful going forward.
NOFS, NOIO scopes are both compatible with NOFAIL and NOWAIT contexts.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2024-07-24 13:31 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-24 8:55 [PATCH 0/5] mm: clarify nofail memory allocation Barry Song
2024-07-24 8:55 ` [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL Barry Song
2024-07-24 12:26 ` Michal Hocko
2024-07-24 22:50 ` Barry Song
2024-07-25 6:08 ` Michal Hocko
2024-07-25 7:00 ` Barry Song
2024-07-29 3:42 ` Jason Wang
2024-07-29 6:05 ` Barry Song
[not found] ` <CACGkMEuv4M_NaUQPHH59MPevGoJJoYb70LykcCODD=nUvik3ZQ@mail.gmail.com>
2024-07-30 3:08 ` Barry Song
2024-07-24 8:55 ` [PATCH 2/5] mm: Document __GFP_NOFAIL must be blockable Barry Song
2024-07-24 11:58 ` Michal Hocko
2024-08-03 23:09 ` Davidlohr Bueso
2024-07-24 8:55 ` [PATCH 3/5] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails Barry Song
2024-07-24 10:03 ` Vlastimil Babka
2024-07-24 10:11 ` Barry Song
2024-07-24 12:10 ` Michal Hocko
2024-07-24 8:55 ` [PATCH 4/5] mm: Introduce GFP_NOFAIL with the inclusion of __GFP_RECLAIM Barry Song
2024-07-24 12:12 ` Michal Hocko
2024-07-24 8:55 ` [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL Barry Song
2024-07-24 9:53 ` Vlastimil Babka
2024-07-24 9:58 ` Barry Song
2024-07-24 13:14 ` Christoph Hellwig
2024-07-24 12:25 ` Michal Hocko
2024-07-24 13:13 ` Christoph Hellwig
2024-07-24 13:21 ` Michal Hocko
2024-07-24 13:23 ` Christoph Hellwig
2024-07-24 13:31 ` Michal Hocko [this message]
2024-07-24 13:33 ` Vlastimil Babka
2024-07-24 13:38 ` Christoph Hellwig
2024-07-24 13:47 ` Michal Hocko
2024-07-24 13:55 ` Christoph Hellwig
2024-07-24 14:39 ` Vlastimil Babka
2024-07-24 14:41 ` Christoph Hellwig
2024-07-25 1:47 ` Barry Song
2024-07-29 9:56 ` Barry Song
2024-07-29 10:03 ` Vlastimil Babka
2024-07-29 10:16 ` Barry Song
2024-07-24 12:17 ` Michal Hocko
2024-07-25 1:38 ` Barry Song
2024-07-25 6:16 ` Michal Hocko
2024-07-26 21:08 ` Davidlohr Bueso
2024-07-29 11:50 ` Michal Hocko
2024-08-03 22:15 ` Davidlohr Bueso
2024-08-05 7:49 ` Michal Hocko
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