On Fri 13-11-15 13:01:16, Vlastimil Babka wrote: > On 11/13/2015 12:47 PM, yalin wang wrote: > >Add page_is_file_cache() for __GFP_FS check, > >otherwise, a Pageswapcache() && PageDirty() page can always be write > >back if the gfp flag is __GFP_FS, this is not the expected behavior. > > I'm not sure I understand your point correctly *), but you seem to imply > that there would be an allocation that has __GFP_FS but doesn't have > __GFP_IO? Are there such allocations and does it make sense? No it doesn't. There is a natural layering here and __GFP_FS allocations should contain __GFP_IO. The patch as is makes only little sense to me. Are you seeing any issue which this is trying to fix? > *) It helps to state which problem you actually observed and are trying to > fix. Or was this found by code inspection? In that case describe the > theoretical problem, as "expected behavior" isn't always understood by > everyone the same. > > >Signed-off-by: yalin wang <yalin.wang2010@xxxxxxxxx> > >--- > > mm/vmscan.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > >diff --git a/mm/vmscan.c b/mm/vmscan.c > >index bd2918e..f8fc8c1 100644 > >--- a/mm/vmscan.c > >+++ b/mm/vmscan.c > >@@ -930,7 +930,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, > > if (page_mapped(page) || PageSwapCache(page)) > > sc->nr_scanned++; > > > >- may_enter_fs = (sc->gfp_mask & __GFP_FS) || > >+ may_enter_fs = (page_is_file_cache(page) && (sc->gfp_mask & __GFP_FS)) || > > (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); > > > > /* > > -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>