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swap: revert special hibernation allocation

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Please revert 2.6.36-rc commit d2997b1042
"hibernation: freeze swap at hibernation".  It complicated matters by
adding a second swap allocation path, just for hibernation; without in any
way fixing the issue that it was intended to address - page reclaim after
fixing the hibernation image might free swap from a page already imaged as
swapcache, letting its swap be reallocated to store a different page of
the image: resulting in data corruption if the imaged page were freed as
clean then swapped back in.  Pages freed to si->swap_map were still in
danger of being reallocated by the alternative allocation path.

I guess it inadvertently fixed slow SSD swap allocation for hibernation,
as reported by Nigel Cunningham: by missing out the discards that occur on
the usual swap allocation path; but that was unintentional, and needs a
separate fix.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ondrej Zary <linux@rainbow-software.org>
Cc: Andrea Gelmini <andrea.gelmini@gmail.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nigel Cunningham <nigel@tuxonice.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins
2010-09-09 16:38:07 -07:00
committed by Linus Torvalds
parent ac8456d6f9
commit 910321ea81
5 changed files with 26 additions and 84 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
kernel/power/hibernate.c
View File

@ -338,7 +338,6 @@ int hibernation_snapshot(int platform_mode)
goto Close;
suspend_console();
hibernation_freeze_swap();
saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
error = dpm_suspend_start(PMSG_FREEZE);
if (error)

1
kernel/power/snapshot.c
View File

@ -1086,7 +1086,6 @@ void swsusp_free(void)
buffer = NULL;
alloc_normal = 0;
alloc_highmem = 0;
hibernation_thaw_swap();
}
/* Helper functions used for the shrinking of memory. */

6
kernel/power/swap.c
View File

@ -136,10 +136,10 @@ sector_t alloc_swapdev_block(int swap)
{
unsigned long offset;
offset = swp_offset(get_swap_for_hibernation(swap));
offset = swp_offset(get_swap_page_of_type(swap));
if (offset) {
if (swsusp_extents_insert(offset))
swap_free_for_hibernation(swp_entry(swap, offset));
swap_free(swp_entry(swap, offset));
else
return swapdev_block(swap, offset);
}
@ -163,7 +163,7 @@ void free_all_swap_pages(int swap)
ext = container_of(node, struct swsusp_extent, node);
rb_erase(node, &swsusp_extents);
for (offset = ext->start; offset <= ext->end; offset++)
swap_free_for_hibernation(swp_entry(swap, offset));
swap_free(swp_entry(swap, offset));
kfree(ext);
}