user/sven/linux.git/mm/migrate.c, branch v3.0.74

mm: compaction: introduce sync-light migration for use by compaction

2012-08-01T19:27:18Z

commit a6bc32b899223a877f595ef9ddc1e89ead5072b8 upstream. Stable note: Not tracked in Buzilla. This was part of a series that reduced interactivity stalls experienced when THP was enabled. These stalls were particularly noticable when copying data to a USB stick but the experiences for users varied a lot. This patch adds a lightweight sync migrate operation MIGRATE_SYNC_LIGHT mode that avoids writing back pages to backing storage. Async compaction maps to MIGRATE_ASYNC while sync compaction maps to MIGRATE_SYNC_LIGHT. For other migrate_pages users such as memory hotplug, MIGRATE_SYNC is used. This avoids sync compaction stalling for an excessive length of time, particularly when copying files to a USB stick where there might be a large number of dirty pages backed by a filesystem that does not support ->writepages. [aarcange@redhat.com: This patch is heavily based on Andrea's work] [akpm@linux-foundation.org: fix fs/nfs/write.c build] [akpm@linux-foundation.org: fix fs/btrfs/disk-io.c build] Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman

mm: compaction: determine if dirty pages can be migrated without blocking within ->migratepage

2012-08-01T19:27:17Z

commit b969c4ab9f182a6e1b2a0848be349f99714947b0 upstream. Stable note: Not tracked in Bugzilla. A fix aimed at preserving page aging information by reducing LRU list churning had the side-effect of reducing THP allocation success rates. This was part of a series to restore the success rates while preserving the reclaim fix. Asynchronous compaction is used when allocating transparent hugepages to avoid blocking for long periods of time. Due to reports of stalling, there was a debate on disabling synchronous compaction but this severely impacted allocation success rates. Part of the reason was that many dirty pages are skipped in asynchronous compaction by the following check; if (PageDirty(page) && !sync && mapping->a_ops->migratepage != migrate_page) rc = -EBUSY; This skips over all mapping aops using buffer_migrate_page() even though it is possible to migrate some of these pages without blocking. This patch updates the ->migratepage callback with a "sync" parameter. It is the responsibility of the callback to fail gracefully if migration would block. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Minchan Kim Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman

mm: migration: clean up unmap_and_move()

2012-08-01T19:27:16Z

commit 0dabec93de633a87adfbbe1d800a4c56cd19d73b upstream. Stable note: Not tracked in Bugzilla. This patch makes later patches easier to apply but has no other impact. unmap_and_move() is one a big messy function. Clean it up. Signed-off-by: Minchan Kim Reviewed-by: KOSAKI Motohiro Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Cc: Mel Gorman Cc: Rik van Riel Cc: Michal Hocko Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman

mm: fix race between mremap and removing migration entry

2011-10-25T05:10:17Z

commit 486cf46f3f9be5f2a966016c1a8fe01e32cde09e upstream. I don't usually pay much attention to the stale "? " addresses in stack backtraces, but this lucky report from Pawel Sikora hints that mremap's move_ptes() has inadequate locking against page migration. 3.0 BUG_ON(!PageLocked(p)) in migration_entry_to_page(): kernel BUG at include/linux/swapops.h:105! RIP: 0010:[] [] migration_entry_wait+0x156/0x160 [] handle_pte_fault+0xae1/0xaf0 [] ? __pte_alloc+0x42/0x120 [] ? do_huge_pmd_anonymous_page+0xab/0x310 [] handle_mm_fault+0x181/0x310 [] ? vma_adjust+0x537/0x570 [] do_page_fault+0x11d/0x4e0 [] ? do_mremap+0x2d5/0x570 [] page_fault+0x1f/0x30 mremap's down_write of mmap_sem, together with i_mmap_mutex or lock, and pagetable locks, were good enough before page migration (with its requirement that every migration entry be found) came in, and enough while migration always held mmap_sem; but not enough nowadays, when there's memory hotremove and compaction. The danger is that move_ptes() lets a migration entry dodge around behind remove_migration_pte()'s back, so it's in the old location when looking at the new, then in the new location when looking at the old. Either mremap's move_ptes() must additionally take anon_vma lock(), or migration's remove_migration_pte() must stop peeking for is_swap_entry() before it takes pagetable lock. Consensus chooses the latter: we prefer to add overhead to migration than to mremapping, which gets used by JVMs and by exec stack setup. Reported-and-tested-by: Paweł Sikora Signed-off-by: Hugh Dickins Acked-by: Andrea Arcangeli Acked-by: Mel Gorman Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

migrate: don't account swapcache as shmem

2011-06-16T22:01:24Z

swapcache will reach the below code path in migrate_page_move_mapping, and swapcache is accounted as NR_FILE_PAGES but it's not accounted as NR_SHMEM. Hugh pointed out we must use PageSwapCache instead of comparing mapping to &swapper_space, to avoid build failure with CONFIG_SWAP=n. Signed-off-by: Andrea Arcangeli Acked-by: Hugh Dickins Cc: stable@kernel.org Signed-off-by: Linus Torvalds

mm: use refcounts for page_lock_anon_vma()

2011-05-25T15:39:19Z

Convert page_lock_anon_vma() over to use refcounts. This is done to prepare for the conversion of anon_vma from spinlock to mutex. Sadly this inceases the cost of page_lock_anon_vma() from one to two atomics, a follow up patch addresses this, lets keep that simple for now. Signed-off-by: Peter Zijlstra Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: KOSAKI Motohiro Acked-by: Hugh Dickins Cc: Benjamin Herrenschmidt Cc: David Miller Cc: Martin Schwidefsky Cc: Russell King Cc: Paul Mundt Cc: Jeff Dike Cc: Richard Weinberger Cc: Tony Luck Cc: Mel Gorman Cc: Nick Piggin Cc: Namhyung Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Fix common misspellings

2011-03-31T14:26:23Z

Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi

memcg: fix ugly initialization of return value is in caller

2011-03-24T02:46:22Z

Remove initialization of vaiable in caller of memory cgroup function. Actually, it's return value of memcg function but it's initialized in caller. Some memory cgroup uses following style to bring the result of start function to the end function for avoiding races. mem_cgroup_start_A(&(*ptr)) /* Something very complicated can happen here. */ mem_cgroup_end_A(*ptr) In some calls, *ptr should be initialized to NULL be caller. But it's ugly. This patch fixes that *ptr is initialized by _start function. Signed-off-by: KAMEZAWA Hiroyuki Acked-by: Johannes Weiner Acked-by: Daisuke Nishimura Cc: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: compaction: Use async migration for __GFP_NO_KSWAPD and enforce no writeback

2011-03-23T00:44:05Z

__GFP_NO_KSWAPD allocations are usually very expensive and not mandatory to succeed as they have graceful fallback. Waiting for I/O in those, tends to be overkill in terms of latencies, so we can reduce their latency by disabling sync migrate. Unfortunately, even with async migration it's still possible for the process to be blocked waiting for a request slot (e.g. get_request_wait in the block layer) when ->writepage is called. To prevent __GFP_NO_KSWAPD blocking, this patch prevents ->writepage being called on dirty page cache for asynchronous migration. Addresses https://bugzilla.kernel.org/show_bug.cgi?id=31142 [mel@csn.ul.ie: Avoid writebacks for NFS, retry locked pages, use bool] Signed-off-by: Andrea Arcangeli Signed-off-by: Mel Gorman Cc: Arthur Marsh Cc: Clemens Ladisch Cc: Johannes Weiner Cc: KAMEZAWA Hiroyuki Cc: Minchan Kim Reported-by: Alex Villacis Lasso Tested-by: Alex Villacis Lasso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: rename drop_anon_vma() to put_anon_vma()

2011-03-23T00:44:03Z

The normal code pattern used in the kernel is: get/put. Signed-off-by: Peter Zijlstra Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Hugh Dickins Reviewed-by: Rik van Riel Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds