On Tue, Jul 20, 2021 at 07:26:35PM +0800, Xiongfeng Wang wrote: > When I added might_sleep() in down_timeout(), I got the following Sorry it is not clear if you are able to reproduce this issue without any other modifications in the mainline kernel ? > Calltrace: > > [ 8.775671] BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:160 > [ 8.777070] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 14, name: cpuhp/0 >From this I guess you are adding sleep after raw_spin_lock_irqsave in down_timeout(kernel/locking/semaphore.c). > > It is because generic_exec_single() will disable local irq before > calling _init_cache_level(). _init_cache_level() use acpi_get_table() to > get the PPTT table, but this function could schedule out. > > To fix this issue, we use a static pointer to record the mapped PPTT > table in the first beginning. Later, we use that pointer to reference > the PPTT table in acpi_find_last_cache_level(). We also modify other > functions in pptt.c to use the pointer to reference PPTT table. > I don't follow this change at all. -- Regards, Sudeep
