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Mon, 21 Jul 2025 07:14:52 +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 bIRKNezofWiNWgAAD6G6ig (envelope-from ); Mon, 21 Jul 2025 07:14:52 +0000 Message-ID: <856ccfc6-f576-4789-8f4d-92b9498527d8@suse.de> Date: Mon, 21 Jul 2025 09:14:52 +0200 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] block: fix module reference leak in mq-deadline I/O scheduler To: Nilay Shroff , linux-block@vger.kernel.org Cc: hch@lst.de, ming.lei@redhat.com, axboe@kernel.dk, gjoyce@ibm.com References: <20250719132722.769536-1-nilay@linux.ibm.com> Content-Language: en-US From: Hannes Reinecke In-Reply-To: <20250719132722.769536-1-nilay@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Level: X-Spam-Score: -4.30 On 7/19/25 15:26, Nilay Shroff wrote: > During probe, when the block layer registers a request queue, it > defaults to the mq-deadline I/O scheduler if the device is single-queue > and the mq-deadline module is available. To determine availability, the > elevator_set_default() invokes elevator_find_get(), which increments the > module's reference count. However, this reference is never released, > resulting in a module reference leak that prevents the mq-deadline module > from being unloaded. > > This patch fixes the issue by ensuring the acquired module reference is > properly released. > > Fixes: 1e44bedbc921 ("block: unifying elevator change") > Signed-off-by: Nilay Shroff > --- > Note: This patch is based on https://lore.kernel.org/all/20250718133232.626418-1-nilay@linux.ibm.com/ > So please apply this patch after the above is merged. > --- > block/elevator.c | 19 +++++++++++++------ > 1 file changed, 13 insertions(+), 6 deletions(-) > Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich