From: sashiko-bot@kernel.org
To: "SJ Park" <sj@kernel.org>
Cc: damon@lists.linux.dev
Subject: Re: [RFC PATCH v1.2 6/8] mm/damon/core: handle extreme memory state in damon_get_node_mem_bp()
Date: Mon, 31 Aug 2026 18:29:50 +0000 [thread overview]
Message-ID: <20260831182950.8B89E1F00A3D@smtp.kernel.org> (raw)
In-Reply-To: <20260831140254.72004-7-sj@kernel.org>
> In an extreme and unlikely situation, si_meminfo_node() might let the
> caller show zero total ram. That could cause a divide by zero in
> damon_get_node_mem_bp(). It could also show free memory larger than the
> total memory. This could cause underflow and make DAMOS temporarily
> make unexpected behavior. Thanks to safety guards in the auto-tuning
> feedback loop, that should not be a real problem, though. Fix the
> problems by respectively returning 100% and 0% for used and free memory
> queries in the corner cases.
>
> The issue was discovered [1] by Sashiko.
>
> [1] https://lore.kernel.org/20260328133216.9697-1-sj@kernel.org
>
> Fixes: 0e1c773b501f ("mm/damon/core: introduce damos quota goal metrics for memory node utilization")
> Cc: <stable@vger.kernel.org> # 6.16.x
> Signed-off-by: SJ Park <sj@kernel.org>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260831140254.72004-1-sj@kernel.org?part=6
next prev parent reply other threads:[~2026-08-31 18:29 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-31 14:02 [RFC PATCH v1.2 0/8] mm/damon: fix DAMOS bugs in core, paddr and vaddr SJ Park
2026-08-31 14:02 ` [RFC PATCH v1.2 1/8] mm/damon/core: skip applying scheme if region split for quota fails SJ Park
2026-08-31 17:45 ` sashiko-bot
2026-08-31 14:02 ` [RFC PATCH v1.2 2/8] mm/damon/paddr: respect folio end for DAMOS_STAT SJ Park
2026-08-31 17:54 ` sashiko-bot
2026-08-31 14:02 ` [RFC PATCH v1.2 3/8] mm/damon/paddr: respect folio end for DAMOS actions except STAT SJ Park
2026-08-31 18:06 ` sashiko-bot
2026-08-31 14:02 ` [RFC PATCH v1.2 4/8] mm/damon/vaddr: respect folio end for DAMOS_STAT SJ Park
2026-08-31 18:14 ` sashiko-bot
2026-08-31 14:02 ` [RFC PATCH v1.2 5/8] mm/damon/vaddr: respect folio end for DAMOS_MIGRATE_{HOT,COLD} SJ Park
2026-08-31 18:23 ` sashiko-bot
2026-08-31 14:02 ` [RFC PATCH v1.2 6/8] mm/damon/core: handle extreme memory state in damon_get_node_mem_bp() SJ Park
2026-08-31 18:29 ` sashiko-bot [this message]
2026-08-31 14:02 ` [RFC PATCH v1.2 7/8] mm/damon/core: handle extreme memory state in get_node_memcg_used_bp() SJ Park
2026-08-31 18:41 ` sashiko-bot
2026-09-01 0:36 ` SJ Park
2026-08-31 14:02 ` [RFC PATCH v1.2 8/8] mm/damon/core: handle extreme memory state in get_in_active_mem_bp() SJ Park
2026-08-31 18:49 ` sashiko-bot
2026-09-01 0:37 ` SJ Park
2026-09-01 0:50 ` [RFC PATCH v1.2 0/8] mm/damon: fix DAMOS bugs in core, paddr and vaddr SJ Park
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