linux-kernel - Re: [PATCH mm] mm/page_alloc: Avoid second trylock of zone->lock

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

Message-ID: <20250331081143.cPXjY7PZ@linutronix.de>
Date: Mon, 31 Mar 2025 10:11:43 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, bpf@...r.kernel.org,
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...nel.org,
	akpm@...ux-foundation.org, peterz@...radead.org, vbabka@...e.cz,
	rostedt@...dmis.org, shakeel.butt@...ux.dev, mhocko@...e.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH mm] mm/page_alloc: Avoid second trylock of zone->lock

On 2025-03-30 17:28:09 [-0700], Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@...nel.org>
> 
> spin_trylock followed by spin_lock will cause extra write cache
> access. If the lock is contended it may cause unnecessary cache
> line bouncing and will execute redundant irq restore/save pair.
> Therefore, check alloc/fpi_flags first and use spin_trylock or
> spin_lock.
> 
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation")
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>

Sebastian