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Wong" , Christoph Hellwig , Alexei Starovoitov , Daniel Borkmann , Meta kernel team , bpf@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+09b7d050e4806540153d@syzkaller.appspotmail.com Subject: Re: [PATCH] lib/buildid: use __kernel_read() for sleepable context Message-ID: References: <20251218005818.614819-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251218005818.614819-1-shakeel.butt@linux.dev> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam02 X-Stat-Signature: qckjuggzazqtm6juyoht8ga5q9rh4h31 X-Rspam-User: X-Rspamd-Queue-Id: 7297C1A0015 X-HE-Tag: 1766034807-454911 X-HE-Meta: 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 1LfL2k0u 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 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 Wed, Dec 17, 2025 at 04:58:18PM -0800, Shakeel Butt wrote: > For the sleepable context, convert freader to use __kernel_read() > instead of direct page cache access via read_cache_folio(). This > simplifies the faultable code path by using the standard kernel file > reading interface which handles all the complexity of reading file data. > > At the moment we are not changing the code for non-sleepable context > which uses filemap_get_folio() and only succeeds if the target folios > are already in memory and up-to-date. The reason is to keep the patch > simple and easier to backport to stable kernels. > > Syzbot repro does not crash the kernel anymore and the selftests run > successfully. > > In the follow up we will make __kernel_read() with IOCB_NOWAIT work for > non-sleepable contexts. In addition, I would like to replace the > secretmem check with a more generic approach and will add fstest for the > buildid code. Getting the code further away from messing with internals is good: Reviewed-by: Christoph Hellwig I do not think making IOCB_NOWAIT never wait is feasily, though for the next step.