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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, Christoph Hellwig Subject: Re: [PATCH bpf v2] lib/buildid: use __kernel_read() for sleepable context Message-Id: <20251218132116.c1edb3ee6688605bd270a666@linux-foundation.org> In-Reply-To: <20251218205505.2415840-1-shakeel.butt@linux.dev> References: <20251218205505.2415840-1-shakeel.butt@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 180F240006 X-Rspamd-Server: rspam03 X-Stat-Signature: 3u6sua8cexyspee751zy6qhqjau3it4d X-Rspam-User: X-HE-Tag: 1766092877-475908 X-HE-Meta: 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 2xt2oe4+ 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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 Thu, 18 Dec 2025 12:55:05 -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. > > Reported-by: syzbot+09b7d050e4806540153d@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=09b7d050e4806540153d > Fixes: ad41251c290d ("lib/buildid: implement sleepable build_id_parse() API") v6.12. > Reviewed-by: Christoph Hellwig > Signed-off-by: Shakeel Butt Thanks, I'll add cc:stable to this due to "crashes the kernel".