From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm: make it clear that gfp reclaim modifiers are valid only for sleepable allocations While it might be really clear to MM developers that gfp reclaim modifiers are applicable only to sleepable allocations (those with __GFP_DIRECT_RECLAIM) it seems that actual users of the API are not always sure. Make it explicit that they are not applicable for GFP_NOWAIT or GFP_ATOMIC allocations which are the most commonly used non-sleepable allocation masks. Link: http://lkml.kernel.org/r/20200403083543.11552-3-mhocko@xxxxxxxxxx Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> Cc: Neil Brown <neilb@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/gfp.h | 2 ++ 1 file changed, 2 insertions(+) --- a/include/linux/gfp.h~mm-make-it-clear-that-gfp-reclaim-modifiers-are-valid-only-for-sleepable-allocations +++ a/include/linux/gfp.h @@ -124,6 +124,8 @@ struct vm_area_struct; * * Reclaim modifiers * ~~~~~~~~~~~~~~~~~ + * Please note that all the following flags are only applicable to sleepable + * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them). * * %__GFP_IO can start physical IO. * _
