From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 975441684B4; Tue, 6 Jan 2026 15:21:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767712864; cv=none; b=gTrabMaASJMRW5L8O6s9pI0d7PPp2pXgu7keQqm90lO2lYAtHb4RbGV3V0GM7bRGYxPUgqZW6XqpgLlA8J0A+qe5xvufhfZ7Zlov86ZWZKD+JPRQJU9t0Fd1hNlN+y+K3EaPjzXAFRJOO68XaaRTiplT3mRKFzEnNMulVcIv++M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767712864; c=relaxed/simple; bh=KS1C9bAwlDhZvSLMwp9flwtHD0RxO1IUENqc9t4uHLI=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=L300JkI56f+J1YzSvX/JX1jYUDMgLu1rXeBO/+HzXm+ZOKWF29NQEKx+xOC2mAq0Nfix0DvymBEml+XmDyYpuaH07LF1OPpK/yWB9fFJM4cd+zHt0bbBaLz0fsXenHMi6TAKd8duQU+gEiQV0U/U6LUEmru0M1YsS8E8m9iFO5g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 384438ABED; Tue, 6 Jan 2026 15:20:59 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf13.hostedemail.com (Postfix) with ESMTPA id ECE9C2000D; Tue, 6 Jan 2026 15:20:55 +0000 (UTC) Date: Tue, 6 Jan 2026 10:21:20 -0500 From: Steven Rostedt To: Vlastimil Babka Cc: Andrew Morton , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Sebastian Andrzej Siewior , Clark Williams , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, stable@vger.kernel.org, kernel test robot , Matthew Wilcox Subject: Re: [PATCH mm-hotfixes] mm/page_alloc: prevent pcp corruption with SMP=n Message-ID: <20260106102120.4272260e@gandalf.local.home> In-Reply-To: <04624b16-40ea-42c6-b687-4013796e4779@suse.cz> References: <20260105-fix-pcp-up-v1-1-5579662d2071@suse.cz> <20260105164036.32a22c2e@gandalf.local.home> <04624b16-40ea-42c6-b687-4013796e4779@suse.cz> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: kadyobb6jxgg53rrgr8pk5kiu7pjqpd4 X-Rspamd-Server: rspamout03 X-Rspamd-Queue-Id: ECE9C2000D X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX19Cnps0ORM9wOahzNOtx0DT319eAQmpInc= X-HE-Tag: 1767712855-198917 X-HE-Meta: U2FsdGVkX18qn3xbopg0HXbkKioqQiII+KS+SESHqD4DmcTs87FqtTwlrJHklBpNtixlk38wVYTWl58BF19c+TgMm92szMg+VQcnCFJNRD4AHB5RYUf1fMNVhQROcMki6PZDC0Yr/gdYibD8NrC5wWG37/dIiBSLdagQmEYQCqe4JL5jxVSUPjcFfM05fbU3ts99MchYGe3AcRK+OZCbq7ODj7gIEfL2XaQLW0BDxwqvZlqdVSGAODffh/iEG18lJF8gLB7q7qfRDRhLXeXY2dl8zEBMD79afbk00Tj1xF5+SjEf+Sp0KISnnd++GCQG On Tue, 6 Jan 2026 09:28:29 +0100 Vlastimil Babka wrote: > >> + */ > >> +#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) > >> +static inline void __flags_noop(unsigned long *flags) { } > >> +#define spin_lock_maybe_irqsave(lock, flags) \ > >> +({ \ > >> + __flags_noop(&(flags)); \ > >> + spin_lock(lock); \ > >> +}) > >> +#define spin_unlock_maybe_irqrestore(lock, flags) \ > >> +({ \ > >> + spin_unlock(lock); \ > >> + __flags_noop(&(flags)); \ > >> +}) > >> +#else > >> +#define spin_lock_maybe_irqsave(lock, flags) spin_lock_irqsave(lock, flags) > >> +#define spin_unlock_maybe_irqrestore(lock, flags) spin_unlock_irqrestore(lock, flags) > >> +#endif > >> + > > > > These are very generic looking names for something specific for > > page_alloc.c. Could you add a prefix of some kind to make it easy to see > > that these are specific to the mm code? > > > > mm_spin_lock_maybe_irqsave() ? > OK, I think it's best like this: Yeah, thanks. -- Steve > > ----8<---- > >From a6da5d9e3db005a2f44f3196814d7253dce21d3e Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka > Date: Tue, 6 Jan 2026 09:23:37 +0100 > Subject: [PATCH] mm/page_alloc: prevent pcp corruption with SMP=n - fix > > Add pcp_ prefix to the spin_lock_irqsave wrappers, per Steven. > With that make them also take pcp pointer and reference the lock > field themselves, to be like the existing pcp trylock wrappers. > > Signed-off-by: Vlastimil Babka > --- > mm/page_alloc.c | 30 ++++++++++++++++-------------- > 1 file changed, 16 insertions(+), 14 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index ec3551d56cde..dd72ff39da8c 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -177,19 +177,21 @@ static inline void __pcp_trylock_noop(unsigned long *flags) { } > */ > #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) > static inline void __flags_noop(unsigned long *flags) { } > -#define spin_lock_maybe_irqsave(lock, flags) \ > +#define pcp_spin_lock_maybe_irqsave(ptr, flags) \ > ({ \ > __flags_noop(&(flags)); \ > - spin_lock(lock); \ > + spin_lock(&(ptr)->lock); \ > })