Hello Jens, It is known that during the resume following a hibernate, especially when using an md RAID1 array created on top of SCSI devices, sometimes the system hangs instead of coming up properly. This patch series fixes this problem. This patch series is an alternative for Ming Lei's "block/scsi: safe SCSI quiescing" patch series. The advantages of this patch series are that a fix for the md driver is included, that no third argument has been added to blk_get_request() and that there is no race between blk_get_request() and SCSI quiescing. These patches have been tested on top of a merge of the block layer for-next branch and Linus' master tree. Linus' master tree includes patch "KVM: x86: Fix the NULL pointer parameter in check_cr_write()" but the block layer for-next branch not yet. Please consider these changes for kernel v4.15. Thanks, Bart. Changes between v4 and v5: - Split blk_set_preempt_only() into two functions as requested by Christoph. - Made blk_get_request() trigger WARN_ONCE() if it is attempted to allocate a request while the system is frozen. This is a big help to identify drivers that submit I/O while the system is frozen. - Since kernel thread freezing is on its way out, reworked the approach for avoiding that the md driver submits I/O while the system is frozen such that the approach no longer depends on the kernel thread freeze mechanism. - Fixed the (theoretical) deadlock in scsi_device_quiesce() that was identified by Ming. Changes between v3 and v4: - Made sure that this patch series not only works for scsi-mq but also for the legacy SCSI stack. - Removed an smp_rmb()/smp_wmb() pair from the hot path and added a comment that explains why that is safe. - Reordered the patches in this patch series. Changes between v2 and v3: - Made md kernel threads freezable. - Changed the approach for quiescing SCSI devices again. - Addressed Ming's review comments. Changes compared to v1 of this patch series: - Changed the approach and rewrote the patch series. Bart Van Assche (7): md: Introduce md_stop_all_writes() md: Neither resync nor reshape while the system is frozen block: Convert RQF_PREEMPT into REQ_PREEMPT block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag scsi: Reduce suspend latency scsi: Set QUEUE_FLAG_PREEMPT_ONLY while quiesced block: Make SCSI device suspend and resume work reliably Ming Lei (1): block: Make q_usage_counter also track legacy requests block/blk-core.c | 67 ++++++++++++++++++++++++++++++++++++++++++----- block/blk-mq-debugfs.c | 2 +- block/blk-mq.c | 14 +++------- block/blk-timeout.c | 2 +- drivers/ide/ide-atapi.c | 3 +-- drivers/ide/ide-io.c | 2 +- drivers/ide/ide-pm.c | 4 +-- drivers/md/md.c | 52 +++++++++++++++++++++++++++++++----- drivers/scsi/scsi_lib.c | 43 ++++++++++++++++++++---------- fs/block_dev.c | 4 +-- include/linux/blk_types.h | 6 +++++ include/linux/blkdev.h | 11 +++++--- 12 files changed, 160 insertions(+), 50 deletions(-) -- 2.14.1
