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Fri, 26 Mar 2021 10:27:51 -0700 (PDT) MIME-Version: 1.0 References: <20210324230759.2213957-1-minchan@kernel.org> In-Reply-To: From: Anders Roxell Date: Fri, 26 Mar 2021 18:27:39 +0100 Message-ID: Subject: Re: [PATCH v8] mm: cma: support sysfs To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , Greg Kroah-Hartman , Suren Baghdasaryan , John Dias , jhubbard@nvidia.com, Matthew Wilcox , digetx@gmail.com, Colin Ian King Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: k6u63e385spub1ywg8c55c8raapc9fbi X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E2F91A0049D6 Received-SPF: none (linaro.org>: No applicable sender policy available) receiver=imf15; identity=mailfrom; envelope-from=""; helo=mail-ed1-f52.google.com; client-ip=209.85.208.52 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616779671-990581 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 26 Mar 2021 at 16:51, Minchan Kim wrote: > > On Fri, Mar 26, 2021 at 02:59:30PM +0100, Anders Roxell wrote: > > On Thu, 25 Mar 2021 at 00:09, Minchan Kim 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@kroah.com/ > > > > > > Tested-by: Dmitry Osipenko > > > Reviewed-by: Dmitry Osipenko > > > Reviewed-by: Greg Kroah-Hartman > > > Reviewed-by: John Hubbard > > > Link: https://lore.kernel.org/linux-mm/20210316100433.17665-1-colin.king@canonical.com/ > > > Addresses-Coverity: ("Dereference after null check") > > > Signed-off-by: Colin Ian King > > > Signed-off-by: Minchan Kim > > > > 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): > > [] _raw_spin_unlock_irqrestore+0x90/0x100 > > [ 132.880740][ C0] hardirqs last disabled at (739758): > > [] enter_el1_irq_or_nmi+0xa4/0xc0 > > [ 132.885801][ C0] softirqs last enabled at (739056): > > [] __do_softirq+0x8b8/0x9ac > > [ 132.890571][ C0] softirqs last disabled at (739051): > > [] __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? > > Hi Anders, > > Dmitry reported the crash(However, your callstack is not the same > and didn't show any CMA stuffs so I am not sure it's same crash) > and posted the fix. > > https://lore.kernel.org/linux-mm/20210324192044.1505747-1-minchan@kernel.org/ > > However, in the end, it was folded into original patchset to replace it. Oh, thank you for letting me know, sorry that I reported on the wrong one. > That is an this v8 patch. So, could you try it? I was able to boot the kernel. Cheers, Anders