On Thu, 25 Mar 2021 at 00:09, Minchan Kim <minchan@xxxxxxxxxx> wrote: > > Since CMA is getting used more widely, it's more important to > keep monitoring CMA statistics for system health since it's > directly related to user experience. > > This patch introduces sysfs statistics for CMA, in order to provide > some basic monitoring of the CMA allocator. > > * the number of CMA page successful allocations > * the number of CMA page allocation failures > > These two values allow the user to calcuate the allocation > failure rate for each CMA area. > > e.g.) > /sys/kernel/mm/cma/WIFI/alloc_pages_[success|fail] > /sys/kernel/mm/cma/SENSOR/alloc_pages_[success|fail] > /sys/kernel/mm/cma/BLUETOOTH/alloc_pages_[success|fail] > > The cma_stat was intentionally allocated by dynamic allocation > to harmonize with kobject lifetime management. > https://lore.kernel.org/linux-mm/YCOAmXqt6dZkCQYs@xxxxxxxxx/ > > Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx> > Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx> > Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx> > Link: https://lore.kernel.org/linux-mm/20210316100433.17665-1-colin.king@xxxxxxxxxxxxx/ > Addresses-Coverity: ("Dereference after null check") > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> When I build an arm64 kernel (allmodconfig - boot selftest) on today's next tag: next-20210326, I see this issue when I'm booting in qemu. [ 0.985891][ T9] Callback from call_rcu_tasks() invoked. [ 1.008860][ T1] smp: Bringing up secondary CPUs ... [ 1.012655][ T1] smp: Brought up 1 node, 1 CPU [ 1.015194][ T1] SMP: Total of 1 processors activated. [ 1.018987][ T1] CPU features: detected: 32-bit EL0 Support [ 1.021995][ T1] CPU features: detected: CRC32 instructions [ 1.026047][ T1] CPU features: detected: 32-bit EL1 Support [ 1.033728][ T1] CPU features: emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching [ 2.140828][ T1] CPU: All CPU(s) started at EL1 [ 2.144773][ T17] alternatives: patching kernel code [ 132.866390][ C0] watchdog: BUG: soft lockup - CPU#0 stuck for 25s! [pgdatinit0:20] [ 132.870865][ C0] Modules linked in: [ 132.873037][ C0] irq event stamp: 739758 [ 132.875308][ C0] hardirqs last enabled at (739757): [<ffff8000126fb3d0>] _raw_spin_unlock_irqrestore+0x90/0x100 [ 132.880740][ C0] hardirqs last disabled at (739758): [<ffff8000126e30a4>] enter_el1_irq_or_nmi+0xa4/0xc0 [ 132.885801][ C0] softirqs last enabled at (739056): [<ffff800010010f98>] __do_softirq+0x8b8/0x9ac [ 132.890571][ C0] softirqs last disabled at (739051): [<ffff80001013742c>] __irq_exit_rcu+0x1ac/0x240 [ 132.895560][ C0] CPU: 0 PID: 20 Comm: pgdatinit0 Not tainted 5.12.0-rc4-next-20210326-00008-g23921ff47279 #1 [ 132.900759][ C0] Hardware name: linux,dummy-virt (DT) [ 132.903637][ C0] pstate: 40400005 (nZcv daif +PAN -UAO -TCO BTYPE=--) [ 132.907212][ C0] pc : _raw_spin_unlock_irqrestore+0xa4/0x100 [ 132.910432][ C0] lr : _raw_spin_unlock_irqrestore+0x90/0x100 [ 132.913647][ C0] sp : ffff000007b9f640 [ 132.915832][ C0] x29: ffff000007b9f640 x28: ffff800016954518 [ 132.919237][ C0] x27: 000000000000000e x26: dead000000000100 [ 132.922689][ C0] x25: dead000000000122 x24: 00000000000559b0 [ 132.926098][ C0] x23: ffff80001550e000 x22: ffff800016954530 [ 132.929479][ C0] x21: ffff800016954518 x20: 0000000000000000 [ 132.932901][ C0] x19: ffff800010f662f4 x18: 0000000000001530 [ 132.936312][ C0] x17: 0000000000001470 x16: 0000000000005518 [ 132.939723][ C0] x15: 0000000000001578 x14: ffff800010189520 [ 132.943107][ C0] x13: ffff8000107592e0 x12: ffff600000f73eb1 [ 132.946520][ C0] x11: 1fffe00000f73eb0 x10: ffff600000f73eb0 [ 132.949914][ C0] x9 : dfff800000000000 x8 : ffff000007b9f587 [ 132.953312][ C0] x7 : 0000000000000001 x6 : 00009fffff08c150 [ 132.956713][ C0] x5 : 0000000000000000 x4 : 0000000000000000 [ 132.960117][ C0] x3 : ffff000007b90040 x2 : 000000000005e6fd [ 132.963521][ C0] x1 : 00000000000000c0 x0 : 0000000000000080 [ 132.966889][ C0] Call trace: [ 132.968667][ C0] _raw_spin_unlock_irqrestore+0xa4/0x100 [ 132.971754][ C0] __debug_check_no_obj_freed+0x1d4/0x2a0 [ 132.974890][ C0] debug_check_no_obj_freed+0x20/0x80 [ 132.977813][ C0] __free_pages_ok+0x5a0/0x740 [ 132.980384][ C0] __free_pages_core+0x24c/0x280 [ 132.983091][ C0] deferred_free_range+0x6c/0xbc [ 132.985826][ C0] deferred_init_maxorder+0x2d0/0x350 [ 132.988735][ C0] deferred_init_memmap_chunk+0xc8/0x124 [ 132.991784][ C0] padata_do_multithreaded+0x15c/0x578 [ 132.994723][ C0] deferred_init_memmap+0x26c/0x364 [ 132.997560][ C0] kthread+0x23c/0x260 [ 132.999851][ C0] ret_from_fork+0x10/0x18 [ 133.002324][ C0] Kernel panic - not syncing: softlockup: hung tasks [ 133.005767][ C0] CPU: 0 PID: 20 Comm: pgdatinit0 Tainted: G L 5.12.0-rc4-next-20210326-00008-g23921ff47279 #1 [ 133.011613][ C0] Hardware name: linux,dummy-virt (DT) [ 133.014435][ C0] Call trace: [ 133.016143][ C0] dump_backtrace+0x0/0x420 [ 133.018617][ C0] show_stack+0x38/0x60 [ 133.020882][ C0] dump_stack+0x1fc/0x2c8 [ 133.023343][ C0] panic+0x304/0x5d8 [ 133.025567][ C0] watchdog_timer_fn+0x4ac/0x500 [ 133.028209][ C0] __run_hrtimer+0x770/0xba0 [ 133.030734][ C0] __hrtimer_run_queues+0x1a0/0x220 [ 133.033537][ C0] hrtimer_run_queues+0x20c/0x240 [ 133.036202][ C0] update_process_times+0xbc/0x1a0 [ 133.038997][ C0] tick_periodic+0x27c/0x2c0 [ 133.041510][ C0] tick_handle_periodic+0x44/0x120 [ 133.044267][ C0] arch_timer_handler_virt+0x68/0xa0 [ 133.047226][ C0] handle_percpu_devid_irq+0x118/0x2a0 [ 133.050229][ C0] __handle_domain_irq+0x150/0x1c0 [ 133.052959][ C0] gic_handle_irq+0x130/0x180 [ 133.055505][ C0] el1_irq+0xc0/0x15c [ 133.057723][ C0] _raw_spin_unlock_irqrestore+0xa4/0x100 [ 133.060792][ C0] __debug_check_no_obj_freed+0x1d4/0x2a0 [ 133.063869][ C0] debug_check_no_obj_freed+0x20/0x80 [ 133.066813][ C0] __free_pages_ok+0x5a0/0x740 [ 133.069409][ C0] __free_pages_core+0x24c/0x280 [ 133.072127][ C0] deferred_free_range+0x6c/0xbc [ 133.074847][ C0] deferred_init_maxorder+0x2d0/0x350 [ 133.077803][ C0] deferred_init_memmap_chunk+0xc8/0x124 [ 133.080834][ C0] padata_do_multithreaded+0x15c/0x578 [ 133.083791][ C0] deferred_init_memmap+0x26c/0x364 [ 133.086614][ C0] kthread+0x23c/0x260 [ 133.088879][ C0] ret_from_fork+0x10/0x18 [ 133.092092][ C0] ---[ end Kernel panic - not syncing: softlockup: hung tasks ]--- Full log [1], and my .config [2]. I bisected down to patch 799815f497e2 ("mm: cma: support sysfs"). When I revert 799815f497e2 ("mm: cma: support sysfs") 7af97692f30d ("mm: cma: fix potential null dereference on pointer cma") The kernel boots fine. Any idea whats happening? Cheers, Anders [1] http://ix.io/2U9S [2] http://ix.io/2Ua3
