[PATCH] mm/vmscan.c:shrink_list(): check PageSwapCache() after add_to_swap()

Nikita Danilov
2004-01-28T16:43:03Z

Hello,

shrink_list() checks PageSwapCache() before calling add_to_swap(), this
means that anonymous page that is going to be added to the swap right
now these checks return false and:

(*) it will be unaccounted for in nr_mapped, and

(*) it won't be written to the swap if gfp_flags include __GFP_IO but
not __GFP_FS.

(Both will happen only on the next round of scanning.)

Patch below just moves may_enter_fs initialization down. I am not sure
about (*nr_mapped) increase though.

Comments?

Nikita.
diff -puN -b mm/vmscan.c~check-PageSwapCache-after-add-to-swap mm/vmscan.c
--- i386/mm/vmscan.c~check-PageSwapCache-after-add-to-swap Wed Jan 28 19:22:14 2004
+++ i386-nikita/mm/vmscan.c Wed Jan 28 19:36:16 2004
@@ -380,8 +380,6 @@ shrink_list(struct list_head *page_list,
(*nr_mapped)++;

BUG_ON(PageActive(page));
- may_enter_fs = (gfp_mask & __GFP_FS) ||
- (PageSwapCache(page) && (gfp_mask & __GFP_IO));

if (PageWriteback(page))
goto keep_locked;
@@ -412,6 +410,9 @@ shrink_list(struct list_head *page_list,
}
#endif /* CONFIG_SWAP */

+ may_enter_fs = (gfp_mask & __GFP_FS) ||
+ (PageSwapCache(page) && (gfp_mask & __GFP_IO));
+
/*
* The page is mapped into the page tables of one or more
* processes. Try to unmap it here.

_