On Tue, Aug 31, 2021 at 04:13:22AM -0700, Guenter Roeck wrote: > Hi, > > On Mon, Aug 09, 2021 at 10:12:15AM +0800, Xiaoming Ni wrote: > > Semaphore is sleeping lock. Add might_sleep() to down*() family > > (with exception of down_trylock()) to detect atomic context sleep. > > > > Previously discussed with Peter Zijlstra, see link: > > https://lore.kernel.org/lkml/20210806082320.GD22037@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx > > > > Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx> > > Acked-by: Will Deacon <will@xxxxxxxxxx> > > This patch results in the following traceback on all arm64 boots with > EFI BIOS. > > The problem is only seen with CONFIG_ACPI_PPTT=y, and thus only on arm64. > > Guenter > > --- > [ 14.048540] BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:163 > [ 14.048700] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 14, name: cpuhp/0 > [ 14.048865] 2 locks held by cpuhp/0/14: > [ 14.048943] #0: ffff8000125799b0 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x38/0x254 > [ 14.049320] #1: ffff8000125799d8 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x38/0x254 > [ 14.049523] irq event stamp: 62 > [ 14.049580] hardirqs last enabled at (61): [<ffff800010269690>] finish_task_switch.isra.0+0xd0/0x2f0 > [ 14.049689] hardirqs last disabled at (62): [<ffff800010313ce8>] generic_exec_single+0x138/0x190 > [ 14.049785] softirqs last enabled at (0): [<ffff8000102245d4>] copy_process+0x634/0x1af4 > [ 14.049876] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 14.050299] CPU: 0 PID: 14 Comm: cpuhp/0 Not tainted 5.14.0-01100-gb91db6a0b52e #1 > [ 14.050452] Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 > [ 14.050694] Call trace: > [ 14.050753] dump_backtrace+0x0/0x19c > [ 14.050839] show_stack+0x1c/0x30 > [ 14.050892] dump_stack_lvl+0x9c/0xd8 > [ 14.050949] dump_stack+0x1c/0x38 > [ 14.050999] ___might_sleep+0x154/0x200 > [ 14.051053] __might_sleep+0x54/0x90 > [ 14.051106] down_timeout+0x34/0x90 > [ 14.051159] acpi_os_wait_semaphore+0x68/0x9c > [ 14.051218] acpi_ut_acquire_mutex+0x50/0xbc > [ 14.051277] acpi_get_table+0x3c/0xc0 > [ 14.051330] acpi_find_last_cache_level+0x44/0x12c > [ 14.051391] _init_cache_level+0xd8/0xe4 > [ 14.051446] generic_exec_single+0xf8/0x190 > [ 14.051502] smp_call_function_single+0x174/0x1e0 This is the patch working as intended.. You simply cannot schedule with interrupts disabled as per the callchain.
