From: Peter Zijlstra <peterz@infradead.org>
To: Dmitry Ilvokhin <d@ilvokhin.com>
Cc: dan.j.williams@intel.com, Vlastimil Babka <vbabka@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Brendan Jackman <jackmanb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>, Zi Yan <ziy@nvidia.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com
Subject: Re: [PATCH 1/8] mm: use zone lock guard in reserve_highatomic_pageblock()
Date: Tue, 28 Apr 2026 13:47:21 +0200 [thread overview]
Message-ID: <20260428114721.GV3102624@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <afCS4d4YccQFtvpi@shell.ilvokhin.com>
On Tue, Apr 28, 2026 at 10:58:41AM +0000, Dmitry Ilvokhin wrote:
> I re-tested my original patchset after rebasing and can still reproduce
> the regression (though smaller). It appears to depend on compiler
> inlining decisions: in some cases the compiler is able to deduplicate
> the cleanup path across multiple return sites, while in others it is
> not.
I'm confused, all this has __always_inline on. And the compilers should
be able to track the assignment of the variable and eliminate the test
themselves if value-tracking excludes NULL.
> Given that, I think we can go further than just removing
> __GUARD_IS_ERR(). It should be possible to eliminate this branch
> entirely and simplify the cleanup flow.
>
> https://lore.kernel.org/all/20260427165037.205337-1-d@ilvokhin.com/
>
> Reposting here to increase visibility, as several people involved in
> this code have participated in this thread already.
>
> Any feedback would be appreciated.
This would require very careful audit of all the current users, it's had
this behaviour from the start.
next prev parent reply other threads:[~2026-04-28 11:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-06 16:05 [PATCH 0/8] mm: introduce zone lock guards Dmitry Ilvokhin
2026-03-06 16:05 ` [PATCH 1/8] mm: use zone lock guard in reserve_highatomic_pageblock() Dmitry Ilvokhin
2026-03-06 17:53 ` Andrew Morton
2026-03-06 18:00 ` Steven Rostedt
2026-03-06 18:24 ` Vlastimil Babka
2026-03-06 18:33 ` Andrew Morton
2026-03-06 18:46 ` Steven Rostedt
2026-03-07 13:16 ` Peter Zijlstra
2026-03-07 14:09 ` Dmitry Ilvokhin
2026-03-09 16:45 ` Peter Zijlstra
2026-03-10 12:57 ` Dmitry Ilvokhin
2026-03-12 23:40 ` Dan Williams
2026-03-13 8:36 ` Peter Zijlstra
2026-04-28 10:58 ` Dmitry Ilvokhin
2026-04-28 11:47 ` Peter Zijlstra [this message]
2026-04-28 13:41 ` Dmitry Ilvokhin
2026-03-26 18:04 ` Dmitry Ilvokhin
2026-03-26 18:51 ` Andrew Morton
2026-03-06 16:05 ` [PATCH 2/8] mm: use zone lock guard in unset_migratetype_isolate() Dmitry Ilvokhin
2026-03-06 16:05 ` [PATCH 3/8] mm: use zone lock guard in unreserve_highatomic_pageblock() Dmitry Ilvokhin
2026-03-06 16:10 ` Steven Rostedt
2026-03-06 16:05 ` [PATCH 4/8] mm: use zone lock guard in set_migratetype_isolate() Dmitry Ilvokhin
2026-03-06 16:05 ` [PATCH 5/8] mm: use zone lock guard in take_page_off_buddy() Dmitry Ilvokhin
2026-03-06 16:05 ` [PATCH 6/8] mm: use zone lock guard in put_page_back_buddy() Dmitry Ilvokhin
2026-03-06 16:05 ` [PATCH 7/8] mm: use zone lock guard in free_pcppages_bulk() Dmitry Ilvokhin
2026-03-06 16:05 ` [PATCH 8/8] mm: use zone lock guard in __offline_isolated_pages() Dmitry Ilvokhin
2026-03-06 16:15 ` [PATCH 0/8] mm: introduce zone lock guards Steven Rostedt
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