Both unionfs and memcgroups pose challenges to tmpfs and shmem. To help
fix, it's best to move the swap swizzling functions from swap_state.c
to shmem.c. As a preliminary to that, move swap stats updating down
into __add_to_swap_cache, which will remain internal to swap_state.c.
Well, actually, just move down the incrementation of add_total: remove
noent_race and exist_race completely, they are relics of my 2.4.11 testing.
Alt-SysRq-m users will be thrilled if 2.6.25 is at last free of "race M+N"s.
Signed-off-by: Hugh Dickins <[email protected]>
---
checkpatch.pl would like me to add a KERN_level to the printk, but that's
not something I want to get into here: this is one of a sequence of printks,
some of which are per-arch, with different KERN_levels in different archs.
Perhaps the remaining add/delete/find swap stats should be junked too;
but they are of more general significance, so leave them for now. Nor do I
want to get into removing that irritatingly repeated "Free swap" right now.
mm/swap_state.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
--- 2.6.24-rc5-mm1/mm/swap_state.c 2007-12-05 10:38:45.000000000 +0000
+++ tmpfs1/mm/swap_state.c 2007-12-05 16:42:16.000000000 +0000
@@ -52,16 +52,13 @@ static struct {
unsigned long del_total;
unsigned long find_success;
unsigned long find_total;
- unsigned long noent_race;
- unsigned long exist_race;
} swap_cache_info;
void show_swap_cache_info(void)
{
- printk("Swap cache: add %lu, delete %lu, find %lu/%lu, race %lu+%lu\n",
+ printk("Swap cache: add %lu, delete %lu, find %lu/%lu\n",
swap_cache_info.add_total, swap_cache_info.del_total,
- swap_cache_info.find_success, swap_cache_info.find_total,
- swap_cache_info.noent_race, swap_cache_info.exist_race);
+ swap_cache_info.find_success, swap_cache_info.find_total);
printk("Free swap = %lukB\n", nr_swap_pages << (PAGE_SHIFT - 10));
printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
}
@@ -89,6 +86,7 @@ static int __add_to_swap_cache(struct pa
set_page_private(page, entry.val);
total_swapcache_pages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
+ INC_CACHE_INFO(add_total);
}
write_unlock_irq(&swapper_space.tree_lock);
radix_tree_preload_end();
@@ -102,10 +100,9 @@ static int add_to_swap_cache(struct page
int error;
BUG_ON(PageLocked(page));
- if (!swap_duplicate(entry)) {
- INC_CACHE_INFO(noent_race);
+ if (!swap_duplicate(entry))
return -ENOENT;
- }
+
SetPageLocked(page);
error = __add_to_swap_cache(page, entry, gfp_mask & GFP_KERNEL);
/*
@@ -114,11 +111,8 @@ static int add_to_swap_cache(struct page
if (error) {
ClearPageLocked(page);
swap_free(entry);
- if (error == -EEXIST)
- INC_CACHE_INFO(exist_race);
return error;
}
- INC_CACHE_INFO(add_total);
return 0;
}
@@ -178,11 +172,9 @@ int add_to_swap(struct page * page, gfp_
case 0: /* Success */
SetPageUptodate(page);
SetPageDirty(page);
- INC_CACHE_INFO(add_total);
return 1;
case -EEXIST:
/* Raced with "speculative" read_swap_cache_async */
- INC_CACHE_INFO(exist_race);
swap_free(entry);
continue;
default:
@@ -225,9 +217,7 @@ int move_to_swap_cache(struct page *page
if (!swap_duplicate(entry))
BUG();
SetPageDirty(page);
- INC_CACHE_INFO(add_total);
- } else if (err == -EEXIST)
- INC_CACHE_INFO(exist_race);
+ }
return err;
}
--
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