On Mon, Feb 11, 2019 at 12:53:55PM +0000, Chintan Pandya wrote: > Some of the page flags, like PG_locked is not supposed to > be set twice. Currently, there is no protection around this > and many callers directly tries to set this bit. Others > follow trylock_page() which is much safer version of the > same. But, for performance issues, we may not want to > implement wait-until-set. So, at least, find out who is > doing double setting and fix them. > > Change-Id: I1295fcb8527ce4b54d5d11c11287fc7516006cf0 > Signed-off-by: Chintan Pandya <[email protected]> > --- > include/linux/page-flags.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index a56a9bd4bc6b..e307775c2b4a 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -208,7 +208,7 @@ static __always_inline int Page##uname(struct page *page) > \ > > #define SETPAGEFLAG(uname, lname, policy) \ > static __always_inline void SetPage##uname(struct page *page) > \ > - { set_bit(PG_##lname, &policy(page, 1)->flags); } > + { WARN_ON(test_and_set_bit(PG_##lname, &policy(page, 1)->flags)); }
You forgot to make this depend on CONFIG_DEBUG_VM. Also, I'm not convinced this is always wrong, inefficient sure, but not wrong in general.
