From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-30.mta0.migadu.com [91.218.175.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5DA1527A47F for ; Fri, 28 Aug 2026 18:56:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787943393; cv=none; b=UavXasyoeITxwkQV58En0er/6DZ7Mw6PiyRAHBI5BS8WEmTQj2jBG3tiOfZsnZJCJMlAgmS2Bf5iNFAnE+mHqI2lqFLhPURPYr7IioXMISL2dTmhhrQgtkb5U7M9tvSdX6P0TYKOytHasANWzfuJI3vnK785ji3eHesjT3BF4nU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787943393; c=relaxed/simple; bh=COHTECr9DeZAX32asUSS//tsR/rFjizcv3IDQHcOnVU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=T9H40XAfI57QswpuAeumI+xYXgUzv54a7fSMCkSlMm5Ehr1cE3UeLoIYNCWD8ykucNMUVSho6qGLGAERXNluOnu8nlAYr41cj5zMiAF4WdFToE7nZlmGF0DZjL5Wo2Z2nf6TLUnwbrg8GhhmdbZu9FLA3t8k/eazBMygDXGRAD0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=D27vTXo3; arc=none smtp.client-ip=91.218.175.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="D27vTXo3" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=COHTECr9DeZAX32asUSS//tsR/rFjizcv3IDQHcOnVU=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787943387; v=1; x=1788548187; b=D27vTXo3I0zVioIGEzXP/NUMSyfjk1F4R4aR0+9ZYgDw0uMHkZStrpg7uYiW5cRvwUe+S76I hyoH9wic34ZB3zA93DHOo2Vce6FS5/8uE/cmrdNzTzPMGtESVYVkD4dNMGCvde6t+RVHYm+/Vv8 S2A5dhriYmOBzgzrngMH4Jew= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id b3b004b6420231b8; Fri, 28 Aug 2026 18:56:26 +0000 X-Mizu-Trace-ID: b3b004b6420231b8 X-Migadu-Flow: FLOW_OUT Date: Fri, 28 Aug 2026 11:56:25 -0700 From: Shakeel Butt To: Rik van Riel Cc: linux-kernel@vger.kernel.org, Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com Subject: Re: [PATCH v2] mm/memcontrol: fix stuck FLUSHING_CACHED_CHARGE bit on isolated cpus Message-ID: References: <20260828135036.7d44361f@fangorn> 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-Disposition: inline In-Reply-To: <20260828135036.7d44361f@fangorn> On Fri, Aug 28, 2026 at 01:50:36PM -0400, Rik van Riel wrote: > When drain_all_stock() sets FLUSHING_CACHED_CHARGE before checking > isolation, schedule_drain_work() can drop the work in a separate RCU > critical section, and housekeeping_update()'s synchronize_rcu() can race > that second check, leaving the flag set. > > drain_local_stock() only clears the bit for work that ran, so the flag > remains set and the stock is never drained again. > > Have schedule_drain_work() return whether the work was queued, and clear > FLUSHING_CACHED_CHARGE in drain_all_stock() when the remote CPU is > isolated, so future drains can retry. > > Fixes: 6a792697a53a ("memcg: do not drain charge pcp caches on remote isolated cpus") > Cc: stable@vger.kernel.org > Suggested-by: Michal Hocko > Suggested-by: Shakeel Butt > Signed-off-by: Rik van Riel Acked-by: Shakeel Butt