On Sat, Feb 15, 2020 at 03:02:06AM -0500, Shijie Luo wrote: > We tested a soft lockup problem in linux 4.19 which could also > be found in linux 5.x. > > When dir inode takes up a large number of blocks, and if the > directory is growing when we are searching, it's possible the > restart branch could be called many times, and the do while loop > could hold cpu a long time. > > Here is the call trace in linux 4.19. > > [ 473.756186] Call trace: > [ 473.756196] dump_backtrace+0x0/0x198 > [ 473.756199] show_stack+0x24/0x30 > [ 473.756205] dump_stack+0xa4/0xcc > [ 473.756210] watchdog_timer_fn+0x300/0x3e8 > [ 473.756215] __hrtimer_run_queues+0x114/0x358 > [ 473.756217] hrtimer_interrupt+0x104/0x2d8 > [ 473.756222] arch_timer_handler_virt+0x38/0x58 > [ 473.756226] handle_percpu_devid_irq+0x90/0x248 > [ 473.756231] generic_handle_irq+0x34/0x50 > [ 473.756234] __handle_domain_irq+0x68/0xc0 > [ 473.756236] gic_handle_irq+0x6c/0x150 > [ 473.756238] el1_irq+0xb8/0x140 > [ 473.756286] ext4_es_lookup_extent+0xdc/0x258 [ext4] > [ 473.756310] ext4_map_blocks+0x64/0x5c0 [ext4] > [ 473.756333] ext4_getblk+0x6c/0x1d0 [ext4] > [ 473.756356] ext4_bread_batch+0x7c/0x1f8 [ext4] > [ 473.756379] ext4_find_entry+0x124/0x3f8 [ext4] > [ 473.756402] ext4_lookup+0x8c/0x258 [ext4] > [ 473.756407] __lookup_hash+0x8c/0xe8 > [ 473.756411] filename_create+0xa0/0x170 > [ 473.756413] do_mkdirat+0x6c/0x140 > [ 473.756415] __arm64_sys_mkdirat+0x28/0x38 > [ 473.756419] el0_svc_common+0x78/0x130 > [ 473.756421] el0_svc_handler+0x38/0x78 > [ 473.756423] el0_svc+0x8/0xc > [ 485.755156] watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [tmp:5149] > > Add cond_resched() to avoid soft lockup and to provide a better > system responding. > > Signed-off-by: Shijie Luo <luoshijie1@xxxxxxxxxx> Thanks, applied. - Ted
