Messages in this thread Patch in this message | | | Subject | Re: [RFC PATCH v2] scsi: fix oops in scsi_uninit_cmd() | From | Bart Van Assche <> | Date | Thu, 21 Mar 2019 11:39:02 -0700 |
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On Sat, 2019-03-16 at 10:09 +0800, Jason Yan wrote: > If we remove the scsi disk when running io with fio, oops occured with > the following condition. > > [scsi_eh_0] [fio] > scsi_end_request > ->blk_update_request > ->end_bio(io returned to userspace) > close > ->sd_release > ->scsi_disk_put > ->scsi_disk_release > ->disk->private_data = NULL; > > ->scsi_mq_uninit_cmd > ->scsi_uninit_cmd > ->scsi_cmd_to_driver > ->drv is NULL, Oops > > There is a small window between blk_update_request() and > scsi_mq_uninit_cmd() that scsi disk may have been released. This will > cause a oops like below: > > Unable to handle kernel NULL pointer dereference at virtual address > 0000000000000000 > s/sync.c:67, func=xfer, error=In[11347.116050] Mem abort info: > put/output error > [11347.121598] ESR = 0x96000006 > [11347.126200] Exception class = DABT (current EL), IL = 32 bits > [11347.132117] SET = 0, FnV = 0 > [11347.135170] EA = 0, S1PTW = 0 > [11347.138308] Data abort info: > [11347.141186] ISV = 0, ISS = 0x00000006 > [11347.145019] CM = 0, WnR = 0 > [11347.147977] user pgtable: 4k pages, 48-bit VAs, pgdp = > 00000000a67aece2 > [11347.154591] [0000000000000000] pgd=0000002f90774003, > pud=0000002fab098003, pmd=0000000000000000 > [11347.163304] Internal error: Oops: 96000006 [#1] PREEMPT SMP > [11347.168870] Modules linked in: hisi_sas_v3_hw hisi_sas_main libsas > [11347.175044] CPU: 56 PID: 4294 Comm: scsi_eh_2 Not tainted > 4.19.0-g8052059-dirty #2 > [11347.182600] Hardware name: Huawei D06/D06, BIOS Hisilicon D06 UEFI > RC0 - B601 (V6.01) 11/08/2018 > [11347.191370] pstate: a0c00009 (NzCv daif 㰃繐ε흾㯗
Please verify whether the following patch is a valid alternative for your patch:
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index ed34bfbc3844..745ffdda1bc1 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1408,6 +1408,7 @@ static void sd_release(struct gendisk *disk, fmode_t mode) { struct scsi_disk *sdkp = scsi_disk(disk); struct scsi_device *sdev = sdkp->device; + struct request_queue *q = sdkp->disk->queue; SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n")); @@ -1417,9 +1418,12 @@ static void sd_release(struct gendisk *disk, fmode_t mode) } /* - * XXX and what if there are packets in flight and this close() - * XXX is followed by a "rmmod sd_mod"? + * Wait until any requests that are in progress have completed. + * This is necessary to avoid that e.g. scsi_end_request() crashes + * due to scsi_disk_relase() clearing the disk->private_data pointer. */ + blk_mq_freeze_queue(q); + blk_mq_unfreeze_queue(q); scsi_disk_put(sdkp); } Thanks,
Bart.
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