From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 99F0817C9E; Sat, 25 Oct 2025 05:13:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761369220; cv=none; b=NO93bRp7l0ZGYad2OBaQttSbl2+cq6HkyjnEN9LkBPYxJljBRNSGAgp0s0HfrmbU/aCh0GlF1H2CUJEqmyHwl2uAAnN+Z15pcZ8ukWQ8F29AmcTPMY+HI7WH7Hy4o4dDJbyR6LIfxhYLlwk4XA0i9zch527ckysWqWpmW2lThFM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761369220; c=relaxed/simple; bh=1VhxwTV4sdwWSJRcuCIhvvladHFWeUlpYcqFsLM0igE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s+ZN8h3qpcFTZcLA/cUfup4f6a9I7hO8Gd5Y8itC8ygRlP3I+btKaMZp7ieXO5uyTCs4eZj4xud5ebUejtqG7m8wA/7W2xCpTum9EgYUn4A4Y861oueDVYw3TZPTIBgIKmgTiDw7N+i/XK6WdiQqs+MXtds7TdyahwpYiFdkTFs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IJVI+X5i; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IJVI+X5i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 260A9C4CEF5; Sat, 25 Oct 2025 05:13:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761369220; bh=1VhxwTV4sdwWSJRcuCIhvvladHFWeUlpYcqFsLM0igE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IJVI+X5iwFou8KDDuBWOj4DT71xelY8qD/kWKC5M3CoBf+EPX0m8QUdmHPqw3/hkc 9Ij+aG+7e0DweAJPtOV34CB887xswLV/zPt7R6LDVQiP2DiMYZ/1WcXI3bQh6XPjvR mGUEHnKrRvInYfik/nLX/Vf/4jod5U55GAQ0hiLtSuS5ln1eDv7ue8DkMjJDtO4X4s UgAdiWCB/nmMozeEYlt1EgWB6Bup12CN8XCy5Vsbz1nn/XIivRcTPLpPTgTU+/Rxq8 dOwU4rs70rOwmKL12PT34LWIJEc+MrxGFcZ1gELYvlK7vyda5vO9EJy8Q6ea7W55lH tRaDDhk6bygbw== Date: Fri, 24 Oct 2025 22:13:39 -0700 From: "Darrick J. Wong" To: Matthew Wilcox Cc: libaokun@huaweicloud.com, linux-ext4@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, linux-kernel@vger.kernel.org, kernel@pankajraghav.com, mcgrof@kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, yi.zhang@huawei.com, yangerkun@huawei.com, chengzhihao1@huawei.com, libaokun1@huawei.com Subject: Re: [PATCH 22/25] fs/buffer: prevent WARN_ON in __alloc_pages_slowpath() when BS > PS Message-ID: <20251025051339.GR6170@frogsfrogsfrogs> References: <20251025032221.2905818-1-libaokun@huaweicloud.com> <20251025032221.2905818-23-libaokun@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-ext4@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: On Sat, Oct 25, 2025 at 05:45:29AM +0100, Matthew Wilcox wrote: > On Sat, Oct 25, 2025 at 11:22:18AM +0800, libaokun@huaweicloud.com wrote: > > + while (1) { > > + folio = __filemap_get_folio(mapping, index, fgp_flags, > > + gfp & ~__GFP_NOFAIL); > > + if (!IS_ERR(folio) || !(gfp & __GFP_NOFAIL)) > > + return folio; > > + > > + if (PTR_ERR(folio) != -ENOMEM && PTR_ERR(folio) != -EAGAIN) > > + return folio; > > + > > + memalloc_retry_wait(gfp); > > + } > > No, absolutely not. We're not having open-coded GFP_NOFAIL semantics. > The right way forward is for ext4 to use iomap, not for buffer heads > to support large block sizes. Seconded. --D