The patch titled memcgroup: revert swap_state mods has been added to the -mm tree. Its filename is memcgroup-revert-swap_state-mods.patch *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this ------------------------------------------------------ Subject: memcgroup: revert swap_state mods From: Hugh Dickins <hugh@xxxxxxxxxxx> If we're charging rss and we're charging cache, it seems obvious that we should be charging swapcache - as has been done. But in practice that doesn't work out so well: both swapin readahead and swapoff leave the majority of pages charged to the wrong cgroup (the cgroup that happened to read them in, rather than the cgroup to which they belong). (Which is why unuse_pte's GFP_KERNEL while holding pte lock never showed up as a problem: no allocation was ever done there, every page read being already charged to the cgroup which initiated the swapoff.) It all works rather better if we leave the charging to do_swap_page and unuse_pte, and do nothing for swapcache itself: revert mm/swap_state.c to what it was before the memory-controller patches. This also speeds up significantly a contained process working at its limit: because it no longer needs to keep waiting for swap writeback to complete. Is it unfair that swap pages become uncharged once they're unmapped, even though they're still clearly private to particular cgroups? For a short while, yes; but PageReclaim arranges for those pages to go to the end of the inactive list and be reclaimed soon if necessary. shmem/tmpfs pages are a distinct case: their charging also benefits from this change, but their second life on the lists as swapcache pages may prove more unfair - that I need to check next. Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx> Cc: Pavel Emelianov <xemul@xxxxxxxxxx> Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> Cc: Paul Menage <menage@xxxxxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Cc: Kirill Korotaev <dev@xxxxx> Cc: Herbert Poetzl <herbert@xxxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swap_state.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff -puN mm/swap_state.c~memcgroup-revert-swap_state-mods mm/swap_state.c --- a/mm/swap_state.c~memcgroup-revert-swap_state-mods +++ a/mm/swap_state.c @@ -17,7 +17,6 @@ #include <linux/backing-dev.h> #include <linux/pagevec.h> #include <linux/migrate.h> -#include <linux/memcontrol.h> #include <asm/pgtable.h> @@ -79,11 +78,6 @@ static int __add_to_swap_cache(struct pa BUG_ON(!PageLocked(page)); BUG_ON(PageSwapCache(page)); BUG_ON(PagePrivate(page)); - - error = mem_cgroup_cache_charge(page, current->mm, gfp_mask); - if (error) - goto out; - error = radix_tree_preload(gfp_mask); if (!error) { write_lock_irq(&swapper_space.tree_lock); @@ -95,14 +89,10 @@ 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); - } else - mem_cgroup_uncharge_page(page); - + } write_unlock_irq(&swapper_space.tree_lock); radix_tree_preload_end(); - } else - mem_cgroup_uncharge_page(page); -out: + } return error; } @@ -143,7 +133,6 @@ void __delete_from_swap_cache(struct pag BUG_ON(PageWriteback(page)); BUG_ON(PagePrivate(page)); - mem_cgroup_uncharge_page(page); radix_tree_delete(&swapper_space.page_tree, page_private(page)); set_page_private(page, 0); ClearPageSwapCache(page); _ Patches currently in -mm which might be from hugh@xxxxxxxxxxx are git-unionfs.patch i386-and-x86_64-randomize-brk-fix-2.patch swapin_readahead-excise-numa-bogosity.patch swapin_readahead-move-and-rearrange-args.patch swapin-needs-gfp_mask-for-loop-on-tmpfs.patch shmem-sgp_quick-and-sgp_fault-redundant.patch shmem_getpage-return-page-locked.patch shmem_file_write-is-redundant.patch swapin-fix-valid_swaphandles-defect.patch swapoff-scan-ptes-preemptibly.patch maps4-add-proportional-set-size-accounting-in-smaps.patch tmpfs-fix-mounts-when-size-is-less-than-the-page-size.patch r-o-bind-mounts-track-number-of-mount-writer-fix-buggy-loop.patch r-o-bind-mounts-track-number-of-mount-writer-fix-buggy-loop-checkpatch-fixes.patch memcgroup-temporarily-revert-swapoff-mod.patch memory-controller-memory-accounting-v7.patch memory-controller-add-per-container-lru-and-reclaim-v7-memcgroup-fix-try_to_free-order.patch memcgroup-reinstate-swapoff-mod.patch memcgroup-fix-zone-isolation-oom.patch memcgroup-revert-swap_state-mods.patch prio_tree-debugging-patch.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html