linux/lib/sbitmap.c, branch v5.0

sbitmap: Protect swap_lock from hardirq

2019-01-15T04:29:57Z

Because we may call blk_mq_get_driver_tag() directly from blk_mq_dispatch_rq_list() without holding any lock, then HARDIRQ may come and the above DEADLOCK is triggered. Commit ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") tries to fix this issue by using 'spin_lock_bh', which isn't enough because we complete request from hardirq context direclty in case of multiqueue. Cc: Clark Williams Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") Cc: Jens Axboe Cc: Ming Lei Cc: Guenter Roeck Cc: Steven Rostedt (VMware) Signed-off-by: Ming Lei Signed-off-by: Linus Torvalds

sbitmap: Protect swap_lock from softirqs

2019-01-14T19:31:18Z

The swap_lock used by sbitmap has a chain with locks taken from softirq, but the swap_lock is not protected from being preempted by softirqs. A chain exists of: sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock Where the sbq->ws[i].wait lock can be taken from softirq context, which means all locks below it in the chain must also be protected from softirqs. Reported-by: Clark Williams Fixes: 58ab5e32e6fd ("sbitmap: silence bogus lockdep IRQ warning") Fixes: ea86ea2cdced ("sbitmap: amortize cost of clearing bits") Cc: Jens Axboe Cc: Ming Lei Cc: Guenter Roeck Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Linus Torvalds

sbitmap: add helpers for add/del wait queue handling

2018-12-20T19:17:05Z

After commit 5d2ee7122c73, users of sbitmap that need wait queue handling must use the provided helpers. But we only added prepare_to_wait()/finish_wait() style helpers, add the equivalent add_wait_queue/list_del wrappers as we.. This is needed to ensure kyber plays by the sbitmap waitqueue rules. Tested-by: Ming Lei Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe

sbitmap: flush deferred clears for resize and shallow gets

2018-12-12T01:39:41Z

We're missing a deferred clear off the shallow get, which can cause a hang. Additionally, when we resize the sbitmap, we should also flush deferred clears for good measure. Ensure we have full coverage on batch clears, even for paths where we would not be doing deferred clear. This makes it less error prone for future additions. Reported-by: Bart Van Assche Tested-by: Ming Lei Signed-off-by: Jens Axboe

sbitmap: silence bogus lockdep IRQ warning

2018-12-10T00:43:20Z

Ming reports that lockdep spews the following trace. What this essentially says is that the sbitmap swap_lock was used inconsistently in IRQ enabled and disabled context, and that is usually indicative of a bug that will cause a deadlock. For this case, it's a false positive. The swap_lock is used from process context only, when we swap the bits in the word and cleared mask. We also end up doing that when we are getting a driver tag, from the blk_mq_mark_tag_wait(), and from there we hold the waitqueue lock with IRQs disabled. However, this isn't from an actual IRQ, it's still process context. In lieu of a better way to fix this, simply always disable interrupts when grabbing the swap_lock if lockdep is enabled. [ 100.967642] ================start test sanity/001================ [ 101.238280] null: module loaded [ 106.093735] [ 106.094012] ===================================================== [ 106.094854] WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [ 106.095759] 4.20.0-rc3_5d2ee7122c73_for-next+ #1 Not tainted [ 106.096551] ----------------------------------------------------- [ 106.097386] fio/1043 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 106.098231] 000000004c43fa71 (&(&sb->map[i].swap_lock)->rlock){+.+.}, at: sbitmap_get+0xd5/0x22c [ 106.099431] [ 106.099431] and this task is already holding: [ 106.100229] 000000007eec8b2f (&(&hctx->dispatch_wait_lock)->rlock){....}, at: blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.101630] which would create a new lock dependency: [ 106.102326] (&(&hctx->dispatch_wait_lock)->rlock){....} -> (&(&sb->map[i].swap_lock)->rlock){+.+.} [ 106.103553] [ 106.103553] but this new dependency connects a SOFTIRQ-irq-safe lock: [ 106.104580] (&sbq->ws[i].wait){..-.} [ 106.104582] [ 106.104582] ... which became SOFTIRQ-irq-safe at: [ 106.105751] _raw_spin_lock_irqsave+0x4b/0x82 [ 106.106284] __wake_up_common_lock+0x119/0x1b9 [ 106.106825] sbitmap_queue_wake_up+0x33f/0x383 [ 106.107456] sbitmap_queue_clear+0x4c/0x9a [ 106.108046] __blk_mq_free_request+0x188/0x1d3 [ 106.108581] blk_mq_free_request+0x23b/0x26b [ 106.109102] scsi_end_request+0x345/0x5d7 [ 106.109587] scsi_io_completion+0x4b5/0x8f0 [ 106.110099] scsi_finish_command+0x412/0x456 [ 106.110615] scsi_softirq_done+0x23f/0x29b [ 106.111115] blk_done_softirq+0x2a7/0x2e6 [ 106.111608] __do_softirq+0x360/0x6ad [ 106.112062] run_ksoftirqd+0x2f/0x5b [ 106.112499] smpboot_thread_fn+0x3a5/0x3db [ 106.113000] kthread+0x1d4/0x1e4 [ 106.113457] ret_from_fork+0x3a/0x50 [ 106.113969] [ 106.113969] to a SOFTIRQ-irq-unsafe lock: [ 106.114672] (&(&sb->map[i].swap_lock)->rlock){+.+.} [ 106.114674] [ 106.114674] ... which became SOFTIRQ-irq-unsafe at: [ 106.116000] ... [ 106.116003] _raw_spin_lock+0x33/0x64 [ 106.116676] sbitmap_get+0xd5/0x22c [ 106.117134] __sbitmap_queue_get+0xe8/0x177 [ 106.117731] __blk_mq_get_tag+0x1e6/0x22d [ 106.118286] blk_mq_get_tag+0x1db/0x6e4 [ 106.118756] blk_mq_get_driver_tag+0x161/0x258 [ 106.119383] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.120043] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.120607] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.121234] __blk_mq_run_hw_queue+0x137/0x17e [ 106.121781] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.122366] blk_mq_run_hw_queue+0x151/0x187 [ 106.122887] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.123492] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.124042] blk_flush_plug_list+0x392/0x3d7 [ 106.124557] blk_finish_plug+0x37/0x4f [ 106.125019] read_pages+0x3ef/0x430 [ 106.125446] __do_page_cache_readahead+0x18e/0x2fc [ 106.126027] force_page_cache_readahead+0x121/0x133 [ 106.126621] page_cache_sync_readahead+0x35f/0x3bb [ 106.127229] generic_file_buffered_read+0x410/0x1860 [ 106.127932] __vfs_read+0x319/0x38f [ 106.128415] vfs_read+0xd2/0x19a [ 106.128817] ksys_read+0xb9/0x135 [ 106.129225] do_syscall_64+0x140/0x385 [ 106.129684] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.130292] [ 106.130292] other info that might help us debug this: [ 106.130292] [ 106.131226] Chain exists of: [ 106.131226] &sbq->ws[i].wait --> &(&hctx->dispatch_wait_lock)->rlock --> &(&sb->map[i].swap_lock)->rlock [ 106.131226] [ 106.132865] Possible interrupt unsafe locking scenario: [ 106.132865] [ 106.133659] CPU0 CPU1 [ 106.134194] ---- ---- [ 106.134733] lock(&(&sb->map[i].swap_lock)->rlock); [ 106.135318] local_irq_disable(); [ 106.136014] lock(&sbq->ws[i].wait); [ 106.136747] lock(&(&hctx->dispatch_wait_lock)->rlock); [ 106.137742] [ 106.138110] lock(&sbq->ws[i].wait); [ 106.138625] [ 106.138625] *** DEADLOCK *** [ 106.138625] [ 106.139430] 3 locks held by fio/1043: [ 106.139947] #0: 0000000076ff0fd9 (rcu_read_lock){....}, at: hctx_lock+0x29/0xe8 [ 106.140813] #1: 000000002feb1016 (&sbq->ws[i].wait){..-.}, at: blk_mq_dispatch_rq_list+0x4ad/0xd7c [ 106.141877] #2: 000000007eec8b2f (&(&hctx->dispatch_wait_lock)->rlock){....}, at: blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.143267] [ 106.143267] the dependencies between SOFTIRQ-irq-safe lock and the holding lock: [ 106.144351] -> (&sbq->ws[i].wait){..-.} ops: 82 { [ 106.144926] IN-SOFTIRQ-W at: [ 106.145314] _raw_spin_lock_irqsave+0x4b/0x82 [ 106.146042] __wake_up_common_lock+0x119/0x1b9 [ 106.146785] sbitmap_queue_wake_up+0x33f/0x383 [ 106.147567] sbitmap_queue_clear+0x4c/0x9a [ 106.148379] __blk_mq_free_request+0x188/0x1d3 [ 106.149148] blk_mq_free_request+0x23b/0x26b [ 106.149864] scsi_end_request+0x345/0x5d7 [ 106.150546] scsi_io_completion+0x4b5/0x8f0 [ 106.151367] scsi_finish_command+0x412/0x456 [ 106.152157] scsi_softirq_done+0x23f/0x29b [ 106.152855] blk_done_softirq+0x2a7/0x2e6 [ 106.153537] __do_softirq+0x360/0x6ad [ 106.154280] run_ksoftirqd+0x2f/0x5b [ 106.155020] smpboot_thread_fn+0x3a5/0x3db [ 106.155828] kthread+0x1d4/0x1e4 [ 106.156526] ret_from_fork+0x3a/0x50 [ 106.157267] INITIAL USE at: [ 106.157713] _raw_spin_lock_irqsave+0x4b/0x82 [ 106.158542] prepare_to_wait_exclusive+0xa8/0x215 [ 106.159421] blk_mq_get_tag+0x34f/0x6e4 [ 106.160186] blk_mq_get_request+0x48e/0xaef [ 106.160997] blk_mq_make_request+0x27e/0xbd2 [ 106.161828] generic_make_request+0x4d1/0x873 [ 106.162661] submit_bio+0x20c/0x253 [ 106.163379] mpage_bio_submit+0x44/0x4b [ 106.164142] mpage_readpages+0x3c2/0x407 [ 106.164919] read_pages+0x13a/0x430 [ 106.165633] __do_page_cache_readahead+0x18e/0x2fc [ 106.166530] force_page_cache_readahead+0x121/0x133 [ 106.167439] page_cache_sync_readahead+0x35f/0x3bb [ 106.168337] generic_file_buffered_read+0x410/0x1860 [ 106.169255] __vfs_read+0x319/0x38f [ 106.169977] vfs_read+0xd2/0x19a [ 106.170662] ksys_read+0xb9/0x135 [ 106.171356] do_syscall_64+0x140/0x385 [ 106.172120] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.173051] } [ 106.173308] ... key at: [] __key.26481+0x0/0x40 [ 106.174219] ... acquired at: [ 106.174646] _raw_spin_lock+0x33/0x64 [ 106.175183] blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.175843] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.176518] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.177262] __blk_mq_run_hw_queue+0x137/0x17e [ 106.177900] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.178591] blk_mq_run_hw_queue+0x151/0x187 [ 106.179207] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.179926] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.180571] blk_flush_plug_list+0x392/0x3d7 [ 106.181187] blk_finish_plug+0x37/0x4f [ 106.181737] __se_sys_io_submit+0x171/0x304 [ 106.182346] do_syscall_64+0x140/0x385 [ 106.182895] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.183607] [ 106.183830] -> (&(&hctx->dispatch_wait_lock)->rlock){....} ops: 1 { [ 106.184691] INITIAL USE at: [ 106.185119] _raw_spin_lock+0x33/0x64 [ 106.185838] blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.186697] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.187551] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.188481] __blk_mq_run_hw_queue+0x137/0x17e [ 106.189307] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.190189] blk_mq_run_hw_queue+0x151/0x187 [ 106.190989] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.191902] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.192739] blk_flush_plug_list+0x392/0x3d7 [ 106.193535] blk_finish_plug+0x37/0x4f [ 106.194269] __se_sys_io_submit+0x171/0x304 [ 106.195059] do_syscall_64+0x140/0x385 [ 106.195794] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.196705] } [ 106.196950] ... key at: [] __key.51231+0x0/0x40 [ 106.197853] ... acquired at: [ 106.198270] lock_acquire+0x280/0x2f3 [ 106.198806] _raw_spin_lock+0x33/0x64 [ 106.199337] sbitmap_get+0xd5/0x22c [ 106.199850] __sbitmap_queue_get+0xe8/0x177 [ 106.200450] __blk_mq_get_tag+0x1e6/0x22d [ 106.201035] blk_mq_get_tag+0x1db/0x6e4 [ 106.201589] blk_mq_get_driver_tag+0x161/0x258 [ 106.202237] blk_mq_dispatch_rq_list+0x5b9/0xd7c [ 106.202902] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.203572] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.204316] __blk_mq_run_hw_queue+0x137/0x17e [ 106.204956] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.205649] blk_mq_run_hw_queue+0x151/0x187 [ 106.206269] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.206997] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.207644] blk_flush_plug_list+0x392/0x3d7 [ 106.208264] blk_finish_plug+0x37/0x4f [ 106.208814] __se_sys_io_submit+0x171/0x304 [ 106.209415] do_syscall_64+0x140/0x385 [ 106.209965] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.210684] [ 106.210904] [ 106.210904] the dependencies between the lock to be acquired [ 106.210905] and SOFTIRQ-irq-unsafe lock: [ 106.212541] -> (&(&sb->map[i].swap_lock)->rlock){+.+.} ops: 1969 { [ 106.213393] HARDIRQ-ON-W at: [ 106.213840] _raw_spin_lock+0x33/0x64 [ 106.214570] sbitmap_get+0xd5/0x22c [ 106.215282] __sbitmap_queue_get+0xe8/0x177 [ 106.216086] __blk_mq_get_tag+0x1e6/0x22d [ 106.216876] blk_mq_get_tag+0x1db/0x6e4 [ 106.217627] blk_mq_get_driver_tag+0x161/0x258 [ 106.218465] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.219326] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.220198] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.221138] __blk_mq_run_hw_queue+0x137/0x17e [ 106.221975] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.222874] blk_mq_run_hw_queue+0x151/0x187 [ 106.223686] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.224597] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.225444] blk_flush_plug_list+0x392/0x3d7 [ 106.226255] blk_finish_plug+0x37/0x4f [ 106.227006] read_pages+0x3ef/0x430 [ 106.227717] __do_page_cache_readahead+0x18e/0x2fc [ 106.228595] force_page_cache_readahead+0x121/0x133 [ 106.229491] page_cache_sync_readahead+0x35f/0x3bb [ 106.230373] generic_file_buffered_read+0x410/0x1860 [ 106.231277] __vfs_read+0x319/0x38f [ 106.231986] vfs_read+0xd2/0x19a [ 106.232666] ksys_read+0xb9/0x135 [ 106.233350] do_syscall_64+0x140/0x385 [ 106.234097] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.235012] SOFTIRQ-ON-W at: [ 106.235460] _raw_spin_lock+0x33/0x64 [ 106.236195] sbitmap_get+0xd5/0x22c [ 106.236913] __sbitmap_queue_get+0xe8/0x177 [ 106.237715] __blk_mq_get_tag+0x1e6/0x22d [ 106.238488] blk_mq_get_tag+0x1db/0x6e4 [ 106.239244] blk_mq_get_driver_tag+0x161/0x258 [ 106.240079] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.240937] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.241806] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.242751] __blk_mq_run_hw_queue+0x137/0x17e [ 106.243579] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.244469] blk_mq_run_hw_queue+0x151/0x187 [ 106.245277] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.246191] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.247044] blk_flush_plug_list+0x392/0x3d7 [ 106.247859] blk_finish_plug+0x37/0x4f [ 106.248749] read_pages+0x3ef/0x430 [ 106.249463] __do_page_cache_readahead+0x18e/0x2fc [ 106.250357] force_page_cache_readahead+0x121/0x133 [ 106.251263] page_cache_sync_readahead+0x35f/0x3bb [ 106.252157] generic_file_buffered_read+0x410/0x1860 [ 106.253084] __vfs_read+0x319/0x38f [ 106.253808] vfs_read+0xd2/0x19a [ 106.254488] ksys_read+0xb9/0x135 [ 106.255186] do_syscall_64+0x140/0x385 [ 106.255943] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.256867] INITIAL USE at: [ 106.257300] _raw_spin_lock+0x33/0x64 [ 106.258033] sbitmap_get+0xd5/0x22c [ 106.258747] __sbitmap_queue_get+0xe8/0x177 [ 106.259542] __blk_mq_get_tag+0x1e6/0x22d [ 106.260320] blk_mq_get_tag+0x1db/0x6e4 [ 106.261072] blk_mq_get_driver_tag+0x161/0x258 [ 106.261902] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.262762] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.263626] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.264571] __blk_mq_run_hw_queue+0x137/0x17e [ 106.265409] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.266302] blk_mq_run_hw_queue+0x151/0x187 [ 106.267111] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.268028] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.268878] blk_flush_plug_list+0x392/0x3d7 [ 106.269694] blk_finish_plug+0x37/0x4f [ 106.270432] read_pages+0x3ef/0x430 [ 106.271139] __do_page_cache_readahead+0x18e/0x2fc [ 106.272040] force_page_cache_readahead+0x121/0x133 [ 106.272932] page_cache_sync_readahead+0x35f/0x3bb [ 106.273811] generic_file_buffered_read+0x410/0x1860 [ 106.274709] __vfs_read+0x319/0x38f [ 106.275407] vfs_read+0xd2/0x19a [ 106.276074] ksys_read+0xb9/0x135 [ 106.276764] do_syscall_64+0x140/0x385 [ 106.277500] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.278417] } [ 106.278676] ... key at: [] __key.26212+0x0/0x40 [ 106.279586] ... acquired at: [ 106.280026] lock_acquire+0x280/0x2f3 [ 106.280559] _raw_spin_lock+0x33/0x64 [ 106.281101] sbitmap_get+0xd5/0x22c [ 106.281610] __sbitmap_queue_get+0xe8/0x177 [ 106.282221] __blk_mq_get_tag+0x1e6/0x22d [ 106.282809] blk_mq_get_tag+0x1db/0x6e4 [ 106.283368] blk_mq_get_driver_tag+0x161/0x258 [ 106.284018] blk_mq_dispatch_rq_list+0x5b9/0xd7c [ 106.284685] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.285371] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.286135] __blk_mq_run_hw_queue+0x137/0x17e [ 106.286806] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.287515] blk_mq_run_hw_queue+0x151/0x187 [ 106.288149] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.289041] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.289912] blk_flush_plug_list+0x392/0x3d7 [ 106.290590] blk_finish_plug+0x37/0x4f [ 106.291238] __se_sys_io_submit+0x171/0x304 [ 106.291864] do_syscall_64+0x140/0x385 [ 106.292534] entry_SYSCALL_64_after_hwframe+0x49/0xbe Reported-by: Ming Lei Tested-by: Guenter Roeck Signed-off-by: Jens Axboe

sbitmap: optimize wakeup check

2018-11-30T21:48:04Z

Even if we have no waiters on any of the sbitmap_queue wait states, we still have to loop every entry to check. We do this for every IO, so the cost adds up. Shift a bit of the cost to the slow path, when we actually have waiters. Wrap prepare_to_wait_exclusive() and finish_wait(), so we can maintain an internal count of how many are currently active. Then we can simply check this count in sbq_wake_ptr() and not have to loop if we don't have any sleepers. Convert the two users of sbitmap with waiting, blk-mq-tag and iSCSI. Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe

sbitmap: ammortize cost of clearing bits

2018-11-30T21:47:45Z

sbitmap maintains a set of words that we use to set and clear bits, with each bit representing a tag for blk-mq. Even though we spread the bits out and maintain a hint cache, one particular bit allocated will end up being cleared in the exact same spot. This introduces batched clearing of bits. Instead of clearing a given bit, the same bit is set in a cleared/free mask instead. If we fail allocating a bit from a given word, then we check the free mask, and batch move those cleared bits at that time. This trades 64 atomic bitops for 2 cmpxchg(). In a threaded poll test case, half the overhead of getting and clearing tags is removed with this change. On another poll test case with a single thread, performance is unchanged. Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe

sbitmap: don't loop for find_next_zero_bit() for !round_robin

2018-11-29T20:58:34Z

If we aren't forced to do round robin tag allocation, just use the allocation hint to find the index for the tag word, don't use it for the offset inside the word. This avoids a potential extra round trip in the bit looping, and since we're fetching this cacheline, we may as well check the whole word from the start. Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe

treewide: kzalloc_node() -> kcalloc_node()

2018-06-12T23:19:22Z

The kzalloc_node() function has a 2-factor argument form, kcalloc_node(). This patch replaces cases of: kzalloc_node(a * b, gfp, node) with: kcalloc_node(a * b, gfp, node) as well as handling cases of: kzalloc_node(a * b * c, gfp, node) with: kzalloc_node(array3_size(a, b, c), gfp, node) as it's slightly less ugly than: kcalloc_node(array_size(a, b), c, gfp, node) This does, however, attempt to ignore constant size factors like: kzalloc_node(4 * 1024, gfp, node) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kzalloc_node( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kzalloc_node( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kzalloc_node( - sizeof(u8) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(__u8) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(char) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(u8) * COUNT + COUNT , ...) | kzalloc_node( - sizeof(__u8) * COUNT + COUNT , ...) | kzalloc_node( - sizeof(char) * COUNT + COUNT , ...) | kzalloc_node( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kzalloc_node + kcalloc_node ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kzalloc_node( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc_node( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc_node( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc_node( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kzalloc_node( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc_node( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc_node( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc_node( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc_node( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kzalloc_node( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kzalloc_node( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kzalloc_node(C1 * C2 * C3, ...) | kzalloc_node( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kzalloc_node( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kzalloc_node( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kzalloc_node( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kzalloc_node(sizeof(THING) * C2, ...) | kzalloc_node(sizeof(TYPE) * C2, ...) | kzalloc_node(C1 * C2 * C3, ...) | kzalloc_node(C1 * C2, ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - (E1) * E2 + E1, E2 , ...) | - kzalloc_node + kcalloc_node ( - (E1) * (E2) + E1, E2 , ...) | - kzalloc_node + kcalloc_node ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook

blk-mq: avoid starving tag allocation after allocating process migrates

2018-05-24T17:00:39Z

When the allocation process is scheduled back and the mapped hw queue is changed, fake one extra wake up on previous queue for compensating wake up miss, so other allocations on the previous queue won't be starved. This patch fixes one request allocation hang issue, which can be triggered easily in case of very low nr_request. The race is as follows: 1) 2 hw queues, nr_requests are 2, and wake_batch is one 2) there are 3 waiters on hw queue 0 3) two in-flight requests in hw queue 0 are completed, and only two waiters of 3 are waken up because of wake_batch, but both the two waiters can be scheduled to another CPU and cause to switch to hw queue 1 4) then the 3rd waiter will wait for ever, since no in-flight request is in hw queue 0 any more. 5) this patch fixes it by the fake wakeup when waiter is scheduled to another hw queue Cc: Reviewed-by: Omar Sandoval Signed-off-by: Ming Lei Modified commit message to make it clearer, and make it apply on top of the 4.18 branch. Signed-off-by: Jens Axboe