> On Nov 15, 2016, at 5:13 PM, Uma Krishnan <ukrishn@xxxxxxxxxxxxxxxxxx> wrote: > > The following Oops is encountered when blk_mq is enabled with the > cxlflash driver: > > [ 2960.817172] Oops: Kernel access of bad area, sig: 11 [#5] > [ 2960.817309] NIP __blk_mq_run_hw_queue+0x278/0x4c0 > [ 2960.817313] LR __blk_mq_run_hw_queue+0x2bc/0x4c0 > [ 2960.817314] Call Trace: > [ 2960.817320] __blk_mq_run_hw_queue+0x2bc/0x4c0 (unreliable) > [ 2960.817324] blk_mq_run_hw_queue+0xd8/0x100 > [ 2960.817329] blk_mq_insert_requests+0x14c/0x1f0 > [ 2960.817333] blk_mq_flush_plug_list+0x150/0x190 > [ 2960.817338] blk_flush_plug_list+0x11c/0x2b0 > [ 2960.817344] blk_finish_plug+0x58/0x80 > [ 2960.817348] __do_page_cache_readahead+0x1c0/0x2e0 > [ 2960.817352] force_page_cache_readahead+0x68/0xd0 > [ 2960.817356] generic_file_read_iter+0x43c/0x6a0 > [ 2960.817359] blkdev_read_iter+0x68/0xa0 > [ 2960.817361] __vfs_read+0x11c/0x180 > [ 2960.817364] vfs_read+0xa4/0x1c0 > [ 2960.817366] SyS_read+0x6c/0x110 > [ 2960.817369] system_call+0x38/0xb4 > > The SCSI blk_mq stack assumes that sg_tablesize is always a non-zero > value with scsi_mq_setup_tags() allocating tags using sg_tablesize. > The cxlflash driver currently uses SG_NONE (0) for the sg_tablesize > as the devices it supports are not capable of scatter gather. This > mismatch of values results in the Oops above. > > To resolve this issue, sg_tablesize for cxlflash can simply be set > to 1, a value which satisfies the constraints in cxlflash and the > lack of support of SG_NONE in SCSI blk_mq. > > Signed-off-by: Uma Krishnan <ukrishn@xxxxxxxxxxxxxxxxxx> Acked-by: Matthew R. Ochs <mrochs@xxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
