linux-kernel - Re: [PATCH] memcg: multi-memcg percpu charge cache

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <rlsgeosg3j7v5nihhbxxxbv3xfy4ejvigihj7lkkbt3n6imyne@2apxx2jm2e57>
Date: Wed, 23 Apr 2025 16:14:33 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Muchun Song <muchun.song@...ux.dev>, 
	Vlastimil Babka <vbabka@...e.cz>, Jakub Kicinski <kuba@...nel.org>, 
	Eric Dumazet <edumazet@...gle.com>, Soheil Hassas Yeganeh <soheil@...gle.com>, linux-mm@...ck.org, 
	cgroups@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Meta kernel team <kernel-team@...a.com>
Subject: Re: [PATCH] memcg: multi-memcg percpu charge cache

Hi Andrew,

Can you please squash the following patch in this one?

From: Shakeel Butt <shakeel.butt@...ux.dev>
Date: Wed, 23 Apr 2025 15:41:18 -0700
Subject: [PATCH] memcg: multi-memcg percpu charge cache - fix

Add BUILD_BUG_ON() for MEMCG_CHARGE_BATCH

Signed-off-by: Shakeel Butt <shakeel.butt@...ux.dev>
---
 mm/memcontrol.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 23894e60c3c0..80ff002b0259 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1909,6 +1909,13 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 	bool evict = true;
 	int i;
 
+	/*
+	 * For now limit MEMCG_CHARGE_BATCH to 127 and less. In future if we
+	 * decide to increase it more than 127 then we will need more careful
+	 * handling of nr_pages[] in struct memcg_stock_pcp.
+	 */
+	BUILD_BUG_ON(MEMCG_CHARGE_BATCH > S8_MAX);
+
 	VM_WARN_ON_ONCE(mem_cgroup_is_root(memcg));
 
 	if (nr_pages > MEMCG_CHARGE_BATCH ||
-- 
2.47.1