From: Lorenzo Stoakes <ljs@kernel.org>
To: Wandun Chen <chenwandun1@gmail.com>
Cc: vbabka@kernel.org, david@kernel.org, rostedt@goodmis.org,
mhiramat@kernel.org, Alexander.Krabler@kuka.com,
hughd@google.com, fvdl@google.com, bigeasy@linutronix.de,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org,
linux-rt-devel@lists.linux.dev, akpm@linux-foundation.org,
surenb@google.com, mhocko@suse.com, jackmanb@google.com,
hannes@cmpxchg.org, ziy@nvidia.com, riel@surriel.com,
liam@infradead.org, harry@kernel.org, jannh@google.com,
lance.yang@linux.dev, mathieu.desnoyers@efficios.com,
matthew.brost@intel.com, joshua.hahnjy@gmail.com,
rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net,
ying.huang@linux.alibaba.com, apopple@nvidia.com,
pfalcato@suse.de
Subject: Re: [PATCH v2 1/4] mm/migrate: do not migrate folios mapped into VM_LOCKED VMAs under compaction
Date: Tue, 7 Jul 2026 14:55:56 +0100 [thread overview]
Message-ID: <ak0EsCeucJarlI7G@lucifer> (raw)
In-Reply-To: <akz7ythMxfIZeT0d@lucifer>
On Tue, Jul 07, 2026 at 02:44:50PM +0100, Lorenzo Stoakes wrote:
> See above about deduplicating.
>
> > + ttu |= TTU_RESPECT_MLOCK;
>
> Hmm. I don't love 'respect mlock'. I guess we only know about the reason
> being compaction here.
>
> But I'm confused anyway. We have the folio, why aren't we just checking for
> PG_mlocked() here instead of getting the rmap to see if it's mapped
> anywhere with VMA_LOCKED_BIT?
Also, since compaction_allow_unevictable() is a function that is accessible
elsewhere, you could literally just have a TTU_MIGRATION here instead and have
the rmap logic call compaction_allow_unevictable() instead rather than this.
And then you could adapt the function I suggested before not to take a reason
parameter but rather a 'is_migration' one instead possibly and then pass (ttu &
TTU_MIGRATION) in.
BUT. I still question whether this is at all needed since you have the folio you
can check for PG_mlocked...
Cheers, Lorenzo
next prev parent reply other threads:[~2026-07-07 13:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-07 12:59 [PATCH v2 0/4] mm: honour compact_unevictable_allowed in mlock and CMA paths Wandun Chen
2026-07-07 12:59 ` [PATCH v2 1/4] mm/migrate: do not migrate folios mapped into VM_LOCKED VMAs under compaction Wandun Chen
2026-07-07 13:44 ` Lorenzo Stoakes
2026-07-07 13:55 ` Lorenzo Stoakes [this message]
2026-07-07 12:59 ` [PATCH v2 2/4] mm/mlock: wait for migration to finish when mlocking a folio Wandun Chen
2026-07-07 14:33 ` Lorenzo Stoakes
2026-07-07 12:59 ` [PATCH v2 3/4] mm/migrate: add tracepoint for folios unmapped during migration Wandun Chen
2026-07-07 12:59 ` [PATCH v2 4/4] mm/mlock: migrate folios out of CMA when mlocking a range Wandun Chen
2026-07-07 13:36 ` Wandun
2026-07-07 14:57 ` Lorenzo Stoakes
2026-07-07 14:54 ` Lorenzo Stoakes
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