From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 07DBA3D4100; Mon, 9 Mar 2026 15:40:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773070820; cv=none; b=Cxk90Od5jl9S6rDGmwY13hr4ncwQJgZbQnSP/mgQ5mL2X3Vk9ZE/GC6g4c3tdcft5KNbNhINcZOj6IU+bON6E1akv0L/jOTkFXlef5WTXM/Sq3XaYR3ClxNbWEObhkO48mDHqBdqwFKgo9zl8FocigRokol1LpBB7zdTs6cAMQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773070820; c=relaxed/simple; bh=BH5jW73g8Nbb+MOjYtZX3x5WWXhBibQwMiTFmg8NspM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s8qNwFN3nOBR2HYTZ83WxNntQW6LdX40dibfgYOmwqaGPKa0Hg5qqd02YUTL3ONzkWYPKLpjsTf+7jYK0Fh1vHlL/Lw8SbTlvQX65hdi1Ha4Te0Rz/bXgRFNz6e36C3NU+TVwPrgFeR5cFV3OaxTWAToy+kLWRQM9QYh5TTOgbs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=HNX5zIrr; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="HNX5zIrr" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=BH5jW73g8Nbb+MOjYtZX3x5WWXhBibQwMiTFmg8NspM=; b=HNX5zIrrNTdc66q+DRzxzxmDJh aC+4Ui7AidvvtENeSLq1FUXKwWB0VMSnDToWmHjVpUYPQmLC6/xFedb1FOJEiIWjLls8fEtBbGcmx RH+PakbfC8kUJOCJM2sRAOCYYvmbgH/ISeP973YAcPe7tCVy392sdlYBCWxTObifkis+favDEVuE1 wZIl304YuROD6csuFgI9Z49+rXJ7oDmnoWnJpWDF1jqkNuv+LTKa3rRQ3kRiA5hghMH+YwFjeD7CQ 02v3UuDQ6kTLCSdaVs1bRdaASzR9XI5mXRer/cAJNiQYcgj/lYVEQhgo+zcHR9cZvM2G0H9YLIngr 8dxwxjVw==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzciM-00000006AaX-0gpX; Mon, 09 Mar 2026 15:40:14 +0000 Date: Mon, 9 Mar 2026 15:40:13 +0000 From: Matthew Wilcox To: Xie Yuanbin Cc: rppt@kernel.org, david.laight.linux@gmail.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, justinstitt@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH] mm: optimize the implementation of WARN_ON_ONCE_GFP() Message-ID: References: <20260309153811.40958-1-qq570070308@gmail.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260309153811.40958-1-qq570070308@gmail.com> On Mon, Mar 09, 2026 at 11:38:11PM +0800, Xie Yuanbin wrote: > As shown in the commit message of commit 242b872239f6a7deacbc > ("include/linux/once_lite.h: fix judgment in WARN_ONCE with clang"), > the code "unlikely(a && b)" may generate poor assembly code if it is > actually "unlikely(a) && unlikely(b)" or "unlikely(a) && b". Why fix this in multiple places in the kernel instead of once in clang?