linux/mm
Johannes Weiner 248ac0e194 mm/vmalloc: remove guard page from between vmap blocks
The vmap allocator is used to, among other things, allocate per-cpu vmap
blocks, where each vmap block is naturally aligned to its own size.
Obviously, leaving a guard page after each vmap area forbids packing vmap
blocks efficiently and can make the kernel run out of possible vmap blocks
long before overall vmap space is exhausted.

The new interface to map a user-supplied page array into linear vmalloc
space (vm_map_ram) insists on allocating from a vmap block (instead of
falling back to a custom area) when the area size is below a certain
threshold.  With heavy users of this interface (e.g.  XFS) and limited
vmalloc space on 32-bit, vmap block exhaustion is a real problem.

Remove the guard page from the core vmap allocator.  vmalloc and the old
vmap interface enforce a guard page on their own at a higher level.

Note that without this patch, we had accidental guard pages after those
vm_map_ram areas that happened to be at the end of a vmap block, but not
between every area.  This patch removes this accidental guard page only.

If we want guard pages after every vm_map_ram area, this should be done
separately.  And just like with vmalloc and the old interface on a
different level, not in the core allocator.

Mel pointed out: "If necessary, the guard page could be reintroduced as a
debugging-only option (CONFIG_DEBUG_PAGEALLOC?).  Otherwise it seems
reasonable."

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Dave Chinner <david@fromorbit.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 08:39:11 -07:00
..
backing-dev.c Fix common misspellings 2011-03-31 11:26:23 -03:00
bootmem.c crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn 2011-03-23 19:47:19 -07:00
bounce.c bounce: call flush_dcache_page() after bounce_copy_vec() 2010-09-09 18:57:25 -07:00
compaction.c mm: compaction: minimise the time IRQs are disabled while isolating pages for migration 2011-03-22 17:44:05 -07:00
debug-pagealloc.c
dmapool.c mm/dmapool.c: use TASK_UNINTERRUPTIBLE in dma_pool_alloc() 2011-01-13 17:32:48 -08:00
fadvise.c readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM 2010-03-06 11:26:25 -08:00
failslab.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
filemap_xip.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
filemap.c x86,mm: make pagefault killable 2011-05-25 08:39:08 -07:00
fremap.c Avoid pgoff overflow in remap_file_pages 2010-09-25 09:34:58 -07:00
highmem.c mm,x86: fix kmap_atomic_push vs ioremap_32.c 2010-10-27 18:03:05 -07:00
huge_memory.c mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups 2011-04-28 11:28:20 -07:00
hugetlb.c Merge branch 'master' into for-next 2011-04-26 10:22:59 +02:00
hwpoison-inject.c Fix common misspellings 2011-03-31 11:26:23 -03:00
init-mm.c mm: provide init_mm mm_context initializer 2010-08-09 20:44:54 -07:00
internal.h mm: nommu: sort mm->mmap list properly 2011-05-25 08:39:05 -07:00
Kconfig mm: compaction: don't depend on HUGETLB_PAGE 2011-01-26 10:50:02 +10:00
Kconfig.debug mm: debug-pagealloc: fix kconfig dependency warning 2011-03-22 17:44:02 -07:00
kmemcheck.c kmemcheck: Fix build errors due to missing slab.h 2010-03-30 22:02:32 +09:00
kmemleak-test.c kmemleak: remove memset by using kzalloc 2011-01-27 18:31:51 +00:00
kmemleak.c kmemleak: Do not return a pointer to an object that kmemleak did not get 2011-05-19 17:35:28 +01:00
ksm.c oom: replace PF_OOM_ORIGIN with toggling oom_score_adj 2011-05-25 08:39:10 -07:00
maccess.c MN10300: Save frame pointer in thread_info struct rather than global var 2010-10-27 17:29:01 +01:00
madvise.c thp: khugepaged: make khugepaged aware about madvise 2011-01-13 17:32:47 -08:00
Makefile bootmem: Separate out CONFIG_NO_BOOTMEM code into nobootmem.c 2011-02-24 14:43:05 +01:00
memblock.c mm/memblock: properly handle overlaps and fix error path 2011-03-22 17:44:09 -07:00
memcontrol.c Fix common misspellings 2011-03-31 11:26:23 -03:00
memory_hotplug.c mm, mem-hotplug: recalculate lowmem_reserve when memory hotplug occurs 2011-05-25 08:39:09 -07:00
memory-failure.c Fix common misspellings 2011-03-31 11:26:23 -03:00
memory.c Don't lock guardpage if the stack is growing up 2011-05-09 16:22:07 -07:00
mempolicy.c mempolicy: remove redundant check in __mpol_equal() 2011-03-22 17:44:04 -07:00
mempool.c mm: remove broken 'kzalloc' mempool 2009-09-22 07:17:35 -07:00
migrate.c Fix common misspellings 2011-03-31 11:26:23 -03:00
mincore.c thp: mincore transparent hugepage support 2011-01-13 17:32:44 -08:00
mlock.c VM: skip the stack guard page lookup in get_user_pages only for mlock 2011-05-04 21:30:28 -07:00
mm_init.c
mmap.c mm: nommu: sort mm->mmap list properly 2011-05-25 08:39:05 -07:00
mmu_context.c exit: fix oops in sync_mm_rss 2010-03-24 16:31:21 -07:00
mmu_notifier.c thp: mmu_notifier_test_young 2011-01-13 17:32:46 -08:00
mmzone.c mm: page allocator: adjust the per-cpu counter threshold when memory is low 2011-01-13 17:32:31 -08:00
mprotect.c thp: mprotect: transparent huge page support 2011-01-13 17:32:44 -08:00
mremap.c mm: avoid wrapping vm_pgoff in mremap() 2011-04-07 07:35:51 -07:00
msync.c sanitize vfs_fsync calling conventions 2010-05-21 18:31:21 -04:00
nobootmem.c Fix common misspellings 2011-03-31 11:26:23 -03:00
nommu.c mm: nommu: fix a compile warning in do_mmap_pgoff() 2011-05-25 08:39:07 -07:00
oom_kill.c oom: replace PF_OOM_ORIGIN with toggling oom_score_adj 2011-05-25 08:39:10 -07:00
page_alloc.c mm/compaction: reverse the change that forbade sync migraton with __GFP_NO_KSWAPD 2011-05-25 08:39:10 -07:00
page_cgroup.c memcg: allocate memory cgroup structures in local nodes 2011-05-11 18:50:45 -07:00
page_io.c block: kill off REQ_UNPLUG 2011-03-10 08:52:27 +01:00
page_isolation.c mm: page_isolation: codeclean fix comment and rm unneeded val init 2010-10-26 16:52:11 -07:00
page-writeback.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
pagewalk.c pagewalk: only split huge pages when necessary 2011-03-22 17:44:04 -07:00
percpu-km.c percpu: clear memory allocated with the km allocator 2010-10-02 10:28:42 +03:00
percpu-vm.c mm: remove gfp mask from pcpu_get_vm_areas 2011-01-13 17:32:34 -08:00
percpu.c Merge branch 'for-2.6.40' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2011-05-24 11:53:42 -07:00
pgtable-generic.c mm/pgtable-generic.c: fix CONFIG_SWAP=n build 2011-01-26 10:49:58 +10:00
prio_tree.c sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00
quicklist.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
readahead.c read-ahead: use plugging 2011-03-10 08:52:26 +01:00
rmap.c [S390] merge page_test_dirty and page_clear_dirty 2011-05-23 10:24:31 +02:00
shmem.c tmpfs: fix highmem swapoff crash regression 2011-05-20 16:23:19 -07:00
slab.c sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00
slob.c mm: Remove support for kmem_cache_name() 2011-01-23 21:00:05 +02:00
slub.c slub: Fix double bit unlock in debug mode 2011-05-25 08:38:24 -07:00
sparse-vmemmap.c tree-wide: fix comment/printk typos 2010-11-01 15:38:34 -04:00
sparse.c Fix common misspellings 2011-03-31 11:26:23 -03:00
swap_state.c block: remove per-queue plugging 2011-03-10 08:52:07 +01:00
swap.c mm: check PageUnevictable in lru_deactivate_fn() 2011-05-11 18:50:44 -07:00
swapfile.c oom: replace PF_OOM_ORIGIN with toggling oom_score_adj 2011-05-25 08:39:10 -07:00
thrash.c mm: pass mm to grab_swap_token 2009-06-23 12:50:05 -07:00
truncate.c mm: deactivate invalidated pages 2011-03-22 17:44:03 -07:00
util.c mm: nommu: sort mm->mmap list properly 2011-05-25 08:39:05 -07:00
vmalloc.c mm/vmalloc: remove guard page from between vmap blocks 2011-05-25 08:39:11 -07:00
vmscan.c mm: vmscan: correctly check if reclaimer should schedule during shrink_slab 2011-05-25 08:39:01 -07:00
vmstat.c mm, mem-hotplug: update pcp->stat_threshold when memory hotplug occur 2011-05-25 08:39:09 -07:00