6.1-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei ming.lei@redhat.com
[ Upstream commit 4373534a9850627a2695317944898eb1283a2db0 ]
Inside scsi_eh_wakeup(), scsi_host_busy() is called & checked with host lock every time for deciding if error handler kthread needs to be waken up.
This can be too heavy in case of recovery, such as:
- N hardware queues
- queue depth is M for each hardware queue
- each scsi_host_busy() iterates over (N * M) tag/requests
If recovery is triggered in case that all requests are in-flight, each scsi_eh_wakeup() is strictly serialized, when scsi_eh_wakeup() is called for the last in-flight request, scsi_host_busy() has been run for (N * M - 1) times, and request has been iterated for (N*M - 1) * (N * M) times.
If both N and M are big enough, hard lockup can be triggered on acquiring host lock, and it is observed on mpi3mr(128 hw queues, queue depth 8169).
Fix the issue by calling scsi_host_busy() outside the host lock. We don't need the host lock for getting busy count because host the lock never covers that.
[mkp: Drop unnecessary 'busy' variables pointed out by Bart]
Cc: Ewan Milne emilne@redhat.com Fixes: 6eb045e092ef ("scsi: core: avoid host-wide host_busy counter for scsi_mq") Signed-off-by: Ming Lei ming.lei@redhat.com Link: https://lore.kernel.org/r/20240112070000.4161982-1-ming.lei@redhat.com Reviewed-by: Ewan D. Milne emilne@redhat.com Reviewed-by: Sathya Prakash Veerichetty safhya.prakash@broadcom.com Tested-by: Sathya Prakash Veerichetty safhya.prakash@broadcom.com Reviewed-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/scsi_error.c | 8 ++++---- drivers/scsi/scsi_lib.c | 2 +- drivers/scsi/scsi_priv.h | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 9a289d6f2e5e..66290961c47c 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -61,11 +61,11 @@ static int scsi_eh_try_stu(struct scsi_cmnd *scmd); static enum scsi_disposition scsi_try_to_abort_cmd(struct scsi_host_template *, struct scsi_cmnd *);
-void scsi_eh_wakeup(struct Scsi_Host *shost) +void scsi_eh_wakeup(struct Scsi_Host *shost, unsigned int busy) { lockdep_assert_held(shost->host_lock);
- if (scsi_host_busy(shost) == shost->host_failed) { + if (busy == shost->host_failed) { trace_scsi_eh_wakeup(shost); wake_up_process(shost->ehandler); SCSI_LOG_ERROR_RECOVERY(5, shost_printk(KERN_INFO, shost, @@ -88,7 +88,7 @@ void scsi_schedule_eh(struct Scsi_Host *shost) if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 || scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) { shost->host_eh_scheduled++; - scsi_eh_wakeup(shost); + scsi_eh_wakeup(shost, scsi_host_busy(shost)); }
spin_unlock_irqrestore(shost->host_lock, flags); @@ -281,7 +281,7 @@ static void scsi_eh_inc_host_failed(struct rcu_head *head)
spin_lock_irqsave(shost->host_lock, flags); shost->host_failed++; - scsi_eh_wakeup(shost); + scsi_eh_wakeup(shost, scsi_host_busy(shost)); spin_unlock_irqrestore(shost->host_lock, flags); }
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d25e1c247253..0e7e9f1e5a02 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -282,7 +282,7 @@ static void scsi_dec_host_busy(struct Scsi_Host *shost, struct scsi_cmnd *cmd) if (unlikely(scsi_host_in_recovery(shost))) { spin_lock_irqsave(shost->host_lock, flags); if (shost->host_failed || shost->host_eh_scheduled) - scsi_eh_wakeup(shost); + scsi_eh_wakeup(shost, scsi_host_busy(shost)); spin_unlock_irqrestore(shost->host_lock, flags); } rcu_read_unlock(); diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h index b14545acb40f..9b5fb30e684b 100644 --- a/drivers/scsi/scsi_priv.h +++ b/drivers/scsi/scsi_priv.h @@ -86,7 +86,7 @@ extern void scmd_eh_abort_handler(struct work_struct *work); extern enum blk_eh_timer_return scsi_timeout(struct request *req); extern int scsi_error_handler(void *host); extern enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *cmd); -extern void scsi_eh_wakeup(struct Scsi_Host *shost); +extern void scsi_eh_wakeup(struct Scsi_Host *shost, unsigned int busy); extern void scsi_eh_scmd_add(struct scsi_cmnd *); void scsi_eh_ready_devs(struct Scsi_Host *shost, struct list_head *work_q,