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Wed, 22 Jul 2026 18:24:56 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 6cI2I/gKYWrWUgAAD6G6ig (envelope-from ); Wed, 22 Jul 2026 18:24:56 +0000 From: Gabriel Krisman Bertazi To: axboe@kernel.dk Cc: io-uring@vger.kernel.org Subject: Re: [PATCH liburing 1/2] test/send_recvmsg: Preserve msghdr until op_recvmsg completes In-Reply-To: <20260722181710.79099-2-krisman@suse.de> Organization: SUSE References: <20260722181710.79099-1-krisman@suse.de> <20260722181710.79099-2-krisman@suse.de> Date: Wed, 22 Jul 2026 14:24:55 -0400 Message-ID: <87ik66evbc.fsf@mailhost.krisman.be> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Score: -4.51 X-Spam-Level: X-Rspamd-Action: no action X-Rspamd-Queue-Id: ECFE57AC19 X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; HAS_ORG_HEADER(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:email,suse.de:dkim]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_NONE(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO Gabriel Krisman Bertazi writes: > msghdr is allocated on the stack at recv_prep, which means it may go out > of scope before the kernel has a chance to complete the operation. This > results in spurious test failures when we reach far enough into recv_fn > to reuse the stack space before op_recvmsg executes. I found it easily > reproducible when compiling with '-O0 -g3' to avoid gcc from optimizing > further local variables out of the stack. In hindsight, I should clarify that by 'test failure' I mean a segmentation fault in the testcase, not a T_EXIT_FAIL. Should have put that in the commit message. -- Gabriel Krisman Bertazi