linux/mm/page_alloc.c, branch v4.3

Merge branch 'akpm' (patches from Andrew)

2015-09-09T00:52:23Z

Merge second patch-bomb from Andrew Morton: "Almost all of the rest of MM. There was an unusually large amount of MM material this time" * emailed patches from Andrew Morton : (141 commits) zpool: remove no-op module init/exit mm: zbud: constify the zbud_ops mm: zpool: constify the zpool_ops mm: swap: zswap: maybe_preload & refactoring zram: unify error reporting zsmalloc: remove null check from destroy_handle_cache() zsmalloc: do not take class lock in zs_shrinker_count() zsmalloc: use class->pages_per_zspage zsmalloc: consider ZS_ALMOST_FULL as migrate source zsmalloc: partial page ordering within a fullness_list zsmalloc: use shrinker to trigger auto-compaction zsmalloc: account the number of compacted pages zsmalloc/zram: introduce zs_pool_stats api zsmalloc: cosmetic compaction code adjustments zsmalloc: introduce zs_can_compact() function zsmalloc: always keep per-class stats zsmalloc: drop unused variable `nr_to_migrate' mm/memblock.c: fix comment in __next_mem_range() mm/page_alloc.c: fix type information of memoryless node memory-hotplug: fix comments in zone_spanned_pages_in_node() and zone_spanned_pages_in_node() ...

mm/page_alloc.c: fix type information of memoryless node

2015-09-08T22:35:28Z

For a memoryless node, the output of get_pfn_range_for_nid are all zero. It will display mem from 0 to -1. Signed-off-by: Zhen Lei Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

memory-hotplug: fix comments in zone_spanned_pages_in_node() and zone_spanned_pages_in_node()

2015-09-08T22:35:28Z

When hot adding a node from add_memory(), we will add memblock first, so the node is not empty. But when called from cpu_up(), the node should be empty. Signed-off-by: Xishi Qiu Cc: Tang Chen Cc: Yasuaki Ishimatsu Cc: Naoya Horiguchi Cc: Vlastimil Babka Cc: Taku Izumi \ Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: change sysctl_lower_zone_reserve_ratio to sysctl_lowmem_reserve_ratio in comments

2015-09-08T22:35:28Z

We use sysctl_lowmem_reserve_ratio rather than sysctl_lower_zone_reserve_ratio to determine how aggressive the kernel is in defending lowmem from the possibility of being captured into pinned user memory. To avoid misleading, correct it in some comments. Signed-off-by: Yaowei Bai Acked-by: Michal Hocko Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: fix a misleading comment

2015-09-08T22:35:28Z

The comment says that the per-cpu batchsize and zone watermarks are determined by present_pages which is definitely wrong, they are both calculated from managed_pages. Fix it. Signed-off-by: Yaowei Bai Acked-by: Michal Hocko Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: rename alloc_pages_exact_node() to __alloc_pages_node()

2015-09-08T22:35:28Z

alloc_pages_exact_node() was introduced in commit 6484eb3e2a81 ("page allocator: do not check NUMA node ID when the caller knows the node is valid") as an optimized variant of alloc_pages_node(), that doesn't fallback to current node for nid == NUMA_NO_NODE. Unfortunately the name of the function can easily suggest that the allocation is restricted to the given node and fails otherwise. In truth, the node is only preferred, unless __GFP_THISNODE is passed among the gfp flags. The misleading name has lead to mistakes in the past, see for example commits 5265047ac301 ("mm, thp: really limit transparent hugepage allocation to local node") and b360edb43f8e ("mm, mempolicy: migrate_to_node should only migrate to node"). Another issue with the name is that there's a family of alloc_pages_exact*() functions where 'exact' means exact size (instead of page order), which leads to more confusion. To prevent further mistakes, this patch effectively renames alloc_pages_exact_node() to __alloc_pages_node() to better convey that it's an optimized variant of alloc_pages_node() not intended for general usage. Both functions get described in comments. It has been also considered to really provide a convenience function for allocations restricted to a node, but the major opinion seems to be that __GFP_THISNODE already provides that functionality and we shouldn't duplicate the API needlessly. The number of users would be small anyway. Existing callers of alloc_pages_exact_node() are simply converted to call __alloc_pages_node(), with the exception of sba_alloc_coherent() which open-codes the check for NUMA_NO_NODE, so it is converted to use alloc_pages_node() instead. This means it no longer performs some VM_BUG_ON checks, and since the current check for nid in alloc_pages_node() uses a 'nid < 0' comparison (which includes NUMA_NO_NODE), it may hide wrong values which would be previously exposed. Both differences will be rectified by the next patch. To sum up, this patch makes no functional changes, except temporarily hiding potentially buggy callers. Restricting the checks in alloc_pages_node() is left for the next patch which can in turn expose more existing buggy callers. Signed-off-by: Vlastimil Babka Acked-by: Johannes Weiner Acked-by: Robin Holt Acked-by: Michal Hocko Acked-by: Christoph Lameter Acked-by: Michael Ellerman Cc: Mel Gorman Cc: David Rientjes Cc: Greg Thelen Cc: Aneesh Kumar K.V Cc: Pekka Enberg Cc: Joonsoo Kim Cc: Naoya Horiguchi Cc: Tony Luck Cc: Fenghua Yu Cc: Arnd Bergmann Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Gleb Natapov Cc: Paolo Bonzini Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Cliff Whickman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: rename and move get/set_freepage_migratetype

2015-09-08T22:35:28Z

The pair of get/set_freepage_migratetype() functions are used to cache pageblock migratetype for a page put on a pcplist, so that it does not have to be retrieved again when the page is put on a free list (e.g. when pcplists become full). Historically it was also assumed that the value is accurate for pages on freelists (as the functions' names unfortunately suggest), but that cannot be guaranteed without affecting various allocator fast paths. It is in fact not needed and all such uses have been removed. The last remaining (but pointless) usage related to pages of freelists is in move_freepages(), which this patch removes. To prevent further confusion, rename the functions to get/set_pcppage_migratetype() and expand their description. Since all the users are now in mm/page_alloc.c, move the functions there from the shared header. Signed-off-by: Vlastimil Babka Acked-by: David Rientjes Acked-by: Joonsoo Kim Cc: Minchan Kim Acked-by: Michal Nazarewicz Cc: Laura Abbott Reviewed-by: Naoya Horiguchi Cc: Seungho Park Cc: Johannes Weiner Cc: "Kirill A. Shutemov" Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, page_isolation: remove bogus tests for isolated pages

2015-09-08T22:35:28Z

The __test_page_isolated_in_pageblock() is used to verify whether all pages in pageblock were either successfully isolated, or are hwpoisoned. Two of the possible state of pages, that are tested, are however bogus and misleading. Both tests rely on get_freepage_migratetype(page), which however has no guarantees about pages on freelists. Specifically, it doesn't guarantee that the migratetype returned by the function actually matches the migratetype of the freelist that the page is on. Such guarantee is not its purpose and would have negative impact on allocator performance. The first test checks whether the freepage_migratetype equals MIGRATE_ISOLATE, supposedly to catch races between page isolation and allocator activity. These races should be fixed nowadays with 51bb1a4093 ("mm/page_alloc: add freepage on isolate pageblock to correct buddy list") and related patches. As explained above, the check wouldn't be able to catch them reliably anyway. For the same reason false positives can happen, although they are harmless, as the move_freepages() call would just move the page to the same freelist it's already on. So removing the test is not a bug fix, just cleanup. After this patch, we assume that all PageBuddy pages are on the correct freelist and that the races were really fixed. A truly reliable verification in the form of e.g. VM_BUG_ON() would be complicated and is arguably not needed. The second test (page_count(page) == 0 && get_freepage_migratetype(page) == MIGRATE_ISOLATE) is probably supposed (the code comes from a big memory isolation patch from 2007) to catch pages on MIGRATE_ISOLATE pcplists. However, pcplists don't contain MIGRATE_ISOLATE freepages nowadays, those are freed directly to free lists, so the check is obsolete. Remove it as well. Signed-off-by: Vlastimil Babka Acked-by: Joonsoo Kim Cc: Minchan Kim Acked-by: Michal Nazarewicz Cc: Laura Abbott Reviewed-by: Naoya Horiguchi Cc: Seungho Park Cc: Johannes Weiner Cc: "Kirill A. Shutemov" Acked-by: Mel Gorman Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, oom: pass an oom order of -1 when triggered by sysrq

2015-09-08T22:35:28Z

The force_kill member of struct oom_control isn't needed if an order of -1 is used instead. This is the same as order == -1 in struct compact_control which requires full memory compaction. This patch introduces no functional change. Signed-off-by: David Rientjes Cc: Sergey Senozhatsky Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, oom: organize oom context into struct

2015-09-08T22:35:28Z

There are essential elements to an oom context that are passed around to multiple functions. Organize these elements into a new struct, struct oom_control, that specifies the context for an oom condition. This patch introduces no functional change. Signed-off-by: David Rientjes Acked-by: Michal Hocko Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds