From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.4]) (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 11D3F2F8EA2 for ; Wed, 13 May 2026 07:55:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778658935; cv=none; b=DCj4w0RaRU7gxd9afjaGCgVS/9End6Q2IZbIW/SdHjynMyzPGSE7hmlPQFMzl0pZgjx59aGWaGPw/GFoUlyI4xP8+ZGrTO37g7z4iVbw3d1MTZIfcFbMVLGQizLbEICIwBDT+Fj/S5x9i2cURKQCQBJL2jHhZNtWdvYXvLZsi0Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778658935; c=relaxed/simple; bh=322iTLnI/4FCWuwKuXDSk4jCTvs6ESFRBWJuuQDtOWI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=evUAj9n9HfkIUT8m2a1df7rP0Uvei1MKRkZVWzYKbDuBkpWUkReENp6ifExHTxG75Tjalh4dkqOmGWug4QTDDeUpLz292LQArnLVEat6NN17yxD4X7+xlbH0QESAhUCQ/JHAdO0zjgykNYr+nrLWiQSJGPsB+X9tNmKap4LEsPQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=G39F/AEo; arc=none smtp.client-ip=117.135.210.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="G39F/AEo" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Message-ID:Date:MIME-Version:Subject:To:From: Content-Type; bh=LHjnHtYT1B9g6E5G4TNVYNhOjM3EynL8pg/KTVuGV6c=; b=G39F/AEoJkcPOY/c+/N33ECm47hcA8qZsmXI4tMYQhr5rbfcRCEIoFWwHALRj2 cIYGKLp43Qk5NS/0Rb/yJ8EDcIUkwl5V6kAcuWzsduyg28cGtVX8K9FU/MUX/2jA BL8XWCG6MTrk6np9YZpYCETBiwQxyIVe59U+GDSWSp+pg= Received: from [192.168.111.49] (unknown []) by gzga-smtp-mtada-g1-0 (Coremail) with SMTP id _____wD3lwBCLgRqXp9HBA--.4805S2; Wed, 13 May 2026 15:54:43 +0800 (CST) Message-ID: <9f0dc54b-d26a-4b0a-9503-c41cdde084bc@163.com> Date: Wed, 13 May 2026 15:55:04 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH v1] mm/shrinker: simplify shrinker_memcg_alloc() using guard() To: Muchun Song Cc: akpm@linux-foundation.org, david@fromorbit.com, qi.zheng@linux.dev, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, wangxuewen References: <20260512085546.368911-1-18810879172@163.com> <616E5E26-BB36-43CD-B086-0F238903B1BF@linux.dev> From: wangxuewen <18810879172@163.com> In-Reply-To: <616E5E26-BB36-43CD-B086-0F238903B1BF@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wD3lwBCLgRqXp9HBA--.4805S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7uF15Cr1rAFyDuF47ZrW7XFb_yoW8Zr1UpF W8GFW7Aa1FvF1kuFW7ZFnaqryjyw409ay8Gr97XFy5t3s3XFnagr4xtw429a4kCa4xGFZ2 q34jqr129F4UAw7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zRP3kNUUUUU= X-CM-SenderInfo: rprymiyqyxmiixs6il2tof0z/xtbC7wQ4LmoELkQohAAA3V Hi,Muchun Song, Thanks for your review. I've updated the patch to v2 following your suggestions. This change is only a local cleanup for this specific function, not part of any large-scale conversion to use the guard() mechanism. Please review v2, thank you. 在 2026/5/12 17:10, Muchun Song 写道: > > >> On May 12, 2026, at 16:55, wangxuewen <18810879172@163.com> wrote: >> >> Use guard(mutex) to automatically handle shrinker_mutex locking and >> unlocking in shrinker_memcg_alloc(). This removes the explicit >> mutex_unlock() call, the goto-based error path, and the redundant >> ret variable, resulting in cleaner and more concise code. >> >> Signed-off-by: wangxuewen >> --- >> mm/shrinker.c | 11 ++++------- >> 1 file changed, 4 insertions(+), 7 deletions(-) >> >> diff --git a/mm/shrinker.c b/mm/shrinker.c >> index 76b3f750cf65..1274130323bf 100644 >> --- a/mm/shrinker.c >> +++ b/mm/shrinker.c >> @@ -222,22 +222,19 @@ static int shrinker_memcg_alloc(struct shrinker *shrinker) >> if (mem_cgroup_kmem_disabled() && !(shrinker->flags & SHRINKER_NONSLAB)) >> return -ENOSYS; >> >> - mutex_lock(&shrinker_mutex); >> + guard(mutex)(&shrinker_mutex); >> id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL); >> if (id < 0) >> - goto unlock; >> + return id; >> >> if (id >= shrinker_nr_max) { >> if (expand_shrinker_info(id)) { >> idr_remove(&shrinker_idr, id); >> - goto unlock; >> + return -ENOMEM; >> } >> } >> shrinker->id = id; >> - ret = 0; >> -unlock: >> - mutex_unlock(&shrinker_mutex); >> - return ret; > > One small thing: since ret is no longer used after this change, > it should be dropped from the declaration to avoid an unused-variable > warning: > > - int id, ret = -ENOMEM; > + int id; > > Otherwise looks good to me. > > Thanks, > Muchun > >> + return 0; >> } >> >> static void shrinker_memcg_remove(struct shrinker *shrinker) >> -- >> 2.25.1 >>