On Thu, Nov 4, 2021 at 3:12 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
On Thu, Nov 04, 2021 at 02:47:03AM +0800, Jimmy Shiu wrote:
> +++ b/mm/filemap.c
> @@ -1271,7 +1271,7 @@ static inline bool folio_trylock_flag(struct folio *folio, int bit_nr,
> /* How many times do we accept lock stealing from under a waiter? */
> int sysctl_page_lock_unfairness = 5;
>
> -static inline int folio_wait_bit_common(struct folio *folio, int bit_nr,
> +static inline __sched int folio_wait_bit_common(struct folio *folio, int bit_nr,
It's not clear to me whether folio_wait_bit_common() needs to be marked
as __sched or whether marking its callers is sufficient, but I'm pretty
sure you forgot to mark put_and_wait_on_page_locked() as __sched, which
is an important one as it's now where we wait for readahead to finish
when reading a file.
I checked the implementation of arch/x86/kernel/process.c # get_wchan() . https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/kernel/process.c#n972
Looks like it unwind the stack and find the 1st non-sched function.
I think we should mark both folio_wait_bit_common() and put_and_wait_on_page_locked()
