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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vCW9i-00000002hpY-0vxi; Sat, 25 Oct 2025 04:45:30 +0000 Date: Sat, 25 Oct 2025 05:45:29 +0100 From: Matthew Wilcox To: libaokun@huaweicloud.com Cc: 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: References: <20251025032221.2905818-1-libaokun@huaweicloud.com> <20251025032221.2905818-23-libaokun@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251025032221.2905818-23-libaokun@huaweicloud.com> X-Rspamd-Server: rspam05 X-Stat-Signature: rpiogemmwsag8bzwedfaeta1tbidq3ya X-Rspam-User: X-Rspamd-Queue-Id: 2E010180008 X-HE-Tag: 1761367541-168431 X-HE-Meta: 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 iy3sXYoi zSTzDBpkhjVr+V0cn5OeMV80GmP3LsDd7WyJGdX22XNoO2wON4i+dpj2lTE1RV8dfFoyIcao2Si/9A+HY08veOTjWIqZ5y7iX1/LW3ZrZv6usm3atwYVXYRnnHohBHSnAfcW5g/c7fRmANjYWbE+IYAnhZSqR2mlH/6J74rQzlEfjBthcI9Rjvvoalauga5y4+siQ4C0LupXsFXFKVjg85HLjPLxPc5zXpscxtX24KOZhSai65bylnawrQA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.