On Mon 16-01-17 11:48:51, Leon Romanovsky wrote: > On Mon, Jan 16, 2017 at 10:37:02AM +0100, Borislav Petkov wrote: > > On Mon, Jan 16, 2017 at 11:28:40AM +0200, Leon Romanovsky wrote: > > > On Mon, Jan 16, 2017 at 10:16:43AM +0100, Borislav Petkov wrote: > > > > From: Borislav Petkov <[email protected]> > > > > > > > > We wanna know who's doing such a thing. Like slab.c does that. > > > > > > > > Signed-off-by: Borislav Petkov <[email protected]> > > > > --- > > > > mm/slub.c | 1 + > > > > 1 file changed, 1 insertion(+) > > > > > > > > diff --git a/mm/slub.c b/mm/slub.c > > > > index 067598a00849..1b0fa7625d6d 100644 > > > > --- a/mm/slub.c > > > > +++ b/mm/slub.c > > > > @@ -1623,6 +1623,7 @@ static struct page *new_slab(struct kmem_cache > > > > *s, gfp_t flags, int node) > > > > flags &= ~GFP_SLAB_BUG_MASK; > > > > pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: > > > > %#x (%pGg). Fix your code!\n", > > > > invalid_mask, &invalid_mask, flags, > > > > &flags); > > > > + dump_stack(); > > > > > > Will it make sense to change these two lines above to WARN(true, .....)? > > > > Should be equivalent. > > Almost, except one point - pr_warn and dump_stack have different log > levels. There is a chance that user won't see pr_warn message above, but > dump_stack will be always present. > > For WARN_XXX, users will always see message and stack at the same time.
On the other hand WARN* will taint the kernel and this sounds a bit overreacting for something like a wrong gfp mask which is perfectly recoverable. Not to mention users who care configured to panic on warning. So while I do not have a strong opinion on this I would rather stay with the dump_stack. -- Michal Hocko SUSE Labs
