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* mm: fix ever-decreasing swap priorityHugh Dickins2008-07-241-24/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | Vegard Nossum has noticed the ever-decreasing negative priority in a swapon /swapoff loop, which eventually would misprioritize when int wraps positive. Not worth spending much code on, but probably better fixed. It's easy to handle the swapping on and off of just one area, but there's not much point if a pair or more still misbehave. To handle the general case, swapoff should compact negative priorities, keeping them always from -1 to -MAX_SWAPFILES. That's a change, but should cause no regression, since these negative (unspecified) priorities are disjoint from the the positive specified priorities 0 to 32767. One small functional difference, which seems appropriate: when swapoff fails to free all swap from a negative priority area, that area is now reinserted at lowest priority, rather than at its original priority. In moving down swapon's setting of priority, I notice that an area is visible to /proc/swaps when it has swap_map set, yet that was being set before all the visible fields were properly filled in: corrected. Signed-off-by: Hugh Dickins <hugh@veritas.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reported-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make CONFIG_MIGRATION available w/o CONFIG_NUMAGerald Schaefer2008-07-242-2/+2
| | | | | | | | | | | | | | | | | | | | | | | We'd like to support CONFIG_MEMORY_HOTREMOVE on s390, which depends on CONFIG_MIGRATION. So far, CONFIG_MIGRATION is only available with NUMA support. This patch makes CONFIG_MIGRATION selectable for architectures that define ARCH_ENABLE_MEMORY_HOTREMOVE. When MIGRATION is enabled w/o NUMA, the kernel won't compile because migrate_vmas() does not know about vm_ops->migrate() and vma_migratable() does not know about policy_zone. To fix this, those two functions can be restricted to '#ifdef CONFIG_NUMA' because they are not being used w/o NUMA. vma_migratable() is moved over from migrate.h to mempolicy.h. [kosaki.motohiro@jp.fujitsu.com: build fix] Acked-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: KOSAKI Motorhiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memory-hotplug: add sysfs removable attribute for hotplug memory removeBadari Pulavarty2008-07-241-0/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Memory may be hot-removed on a per-memory-block basis, particularly on POWER where the SPARSEMEM section size often matches the memory-block size. A user-level agent must be able to identify which sections of memory are likely to be removable before attempting the potentially expensive operation. This patch adds a file called "removable" to the memory directory in sysfs to help such an agent. In this patch, a memory block is considered removable if; o It contains only MOVABLE pageblocks o It contains only pageblocks with free pages regardless of pageblock type On the other hand, a memory block starting with a PageReserved() page will never be considered removable. Without this patch, the user-agent is forced to choose a memory block to remove randomly. Sample output of the sysfs files: ./memory/memory0/removable: 0 ./memory/memory1/removable: 0 ./memory/memory2/removable: 0 ./memory/memory3/removable: 0 ./memory/memory4/removable: 0 ./memory/memory5/removable: 0 ./memory/memory6/removable: 0 ./memory/memory7/removable: 1 ./memory/memory8/removable: 0 ./memory/memory9/removable: 0 ./memory/memory10/removable: 0 ./memory/memory11/removable: 0 ./memory/memory12/removable: 0 ./memory/memory13/removable: 0 ./memory/memory14/removable: 0 ./memory/memory15/removable: 0 ./memory/memory16/removable: 0 ./memory/memory17/removable: 1 ./memory/memory18/removable: 1 ./memory/memory19/removable: 1 ./memory/memory20/removable: 1 ./memory/memory21/removable: 1 ./memory/memory22/removable: 1 Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memory-hotplug: don't calculate vm_total_pages twice when rebuilding ↵Kent Liu2008-07-241-1/+3
| | | | | | | | | | | | | | | zonelists in online_pages() If zonelist is required to be rebuilt in online_pages(), there is no need to recalculate vm_total_pages in that function, as it has been updated in the call build_all_zonelists(). Signed-off-by: Kent Liu <kent.liu@linux.intel.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memory hotplug: small fixes to bootmem freeing for memory hotremoveYasunori Goto2008-07-242-7/+7
| | | | | | | | | | | | | | | | | - Change some naming * Magic -> types * MIX_INFO -> MIX_SECTION_INFO * Change definition of bootmem type from direct hex value - __free_pages_bootmem() becomes __meminit. Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memory hotplug: allocate usemap on the section with pgdatYasunori Goto2008-07-241-1/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Usemaps are allocated on the section which has pgdat by this. Because usemap size is very small, many other sections usemaps are allocated on only one page. If a section has usemap, it can't be removed until removing other sections. This dependency is not desirable for memory removing. Pgdat has similar feature. When a section has pgdat area, it must be the last section for removing on the node. So, if section A has pgdat and section B has usemap for section A, Both sections can't be removed due to dependency each other. To solve this issue, this patch collects usemap on same section with pgdat as much as possible. If other sections doesn't have any dependency, this section will be able to be removed finally. Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Cc: David Miller <davem@davemloft.net> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tony Breeds <tony@bakeyournoodle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove initialization of static per-cpu variablesVegard Nossum2008-07-241-4/+4
| | | | | | | | This was required by some old, no-longer-used gcc on sparc. Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make register_page_bootmem_info_section() staticAdrian Bunk2008-07-241-1/+1
| | | | | | | | | Make the needlessly global register_page_bootmem_info_section() static. Signed-off-by: Adrian Bunk <bunk@kernel.org> Acked-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page_alloc.c: cleanupsAdrian Bunk2008-07-241-12/+13
| | | | | | | | | | | | | | | | | | | | This patch contains the following cleanups: - make the following needlessly global variables static: - required_kernelcore - zone_movable_pfn[] - make the following needlessly global functions static: - move_freepages() - move_freepages_block() - setup_pageset() - find_usable_zone_for_movable() - adjust_zone_range_for_zone_movable() - __absent_pages_in_range() - find_min_pfn_for_node() - find_zone_movable_pfns_for_nodes() Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add alloc_pages_exact() and free_pages_exact()Timur Tabi2008-07-241-0/+53
| | | | | | | | | | | | | | | | | alloc_pages_exact() is similar to alloc_pages(), except that it allocates the minimum number of pages to fulfill the request. This is useful if you want to allocate a very large buffer that is slightly larger than an even power-of-two number of pages. In that case, alloc_pages() will waste a lot of memory. I have a video driver that wants to allocate a 5MB buffer. alloc_pages() wiill waste 3MB of physically-contiguous memory. Signed-off-by: Timur Tabi <timur@freescale.com> Cc: Andi Kleen <andi@firstfloor.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: replace node_boot_start in struct bootmem_dataJohannes Weiner2008-07-241-19/+21
| | | | | | | | | | | | Almost all users of this field need a PFN instead of a physical address, so replace node_boot_start with node_min_pfn. [Lee.Schermerhorn@hp.com: fix spurious BUG_ON() in mark_bootmem()] Signed-off-by: Johannes Weiner <hannes@saeureba.de> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: revisit alloc_bootmem_sectionJohannes Weiner2008-07-241-21/+6
| | | | | | | | | | | | | | Since alloc_bootmem_core does no goal-fallback anymore and just returns NULL if the allocation fails, we might now use it in alloc_bootmem_section without all the fixup code for a misplaced allocation. Also, the limit can be the first PFN of the next section as the semantics is that the limit is _above_ the allocated region, not within. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: Make __alloc_bootmem_low_node fall back to other nodesJohannes Weiner2008-07-241-9/+16
| | | | | | | | | | | __alloc_bootmem_node already does this, make the interface consistent. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: respect goal more likelyJohannes Weiner2008-07-241-38/+54
| | | | | | | | | | | | | | | | | | | | | | The old node-agnostic code tried allocating on all nodes starting from the one with the lowest range. alloc_bootmem_core retried without the goal if it could not satisfy it and so the goal was only respected at all when it happened to be on the first (lowest page numbers) node (or theoretically if allocations failed on all nodes before to the one holding the goal). Introduce a non-panicking helper that starts allocating from the node holding the goal and falls back only after all thes tries failed, thus moving the goal fallback code out of alloc_bootmem_core. Make all other allocation functions benefit from this new helper. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: factor out the marking of a PFN rangeJohannes Weiner2008-07-241-119/+69
| | | | | | | | | | | | | | | | | | | | | | | Introduce new helpers that mark a range that resides completely on a node or node-agnostic ranges that might also span node boundaries. The free/reserve API functions will then directly use these helpers. Note that the free/reserve semantics become more strict: while the prior code took basically arbitrary range arguments and marked the PFNs that happen to fall into that range, the new code requires node-specific ranges to be completely on the node. The node-agnostic requests might span node boundaries as long as the nodes are contiguous. Passing ranges that do not satisfy these criteria is a bug. [akpm@linux-foundation.org: fix printk warnings] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: free/reserve helpersJohannes Weiner2008-07-241-22/+43
| | | | | | | | | | | | Factor out the common operation of marking a range on the bitmap. [akpm@linux-foundation.org: fix various warnings] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: clean up alloc_bootmem_coreJohannes Weiner2008-07-241-136/+76
| | | | | | | | | | | | | | | | | | | | | | alloc_bootmem_core has become quite nasty to read over time. This is a clean rewrite that keeps the semantics. bdata->last_pos has been dropped. bdata->last_success has been renamed to hint_idx and it is now an index relative to the node's range. Since further block searching might start at this index, it is now set to the end of a succeeded allocation rather than its beginning. bdata->last_offset has been renamed to last_end_off to be more clear that it represents the ending address of the last allocation relative to the node. [y-goto@jp.fujitsu.com: fix new alloc_bootmem_core()] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: clean up free_all_bootmem_coreJohannes Weiner2008-07-241-45/+38
| | | | | | | | | | | | Rewrite the code in a more concise way using less variables. [akpm@linux-foundation.org: fix printk warnings] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Yinghai Lu <yhlu.kernel@gmail.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: revisit bootmem descriptor list handlingJohannes Weiner2008-07-241-13/+10
| | | | | | | | | | | | | link_bootmem handles an insertion of a new descriptor into the sorted list in more or less three explicit branches; empty list, insert in between and append. These cases can be expressed implicite. Also mark the sorted list as initdata as it can be thrown away after boot as well. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: revisit bitmap size calculationsJohannes Weiner2008-07-241-18/+9
| | | | | | | | | | | | Reincarnate get_mapsize as bootmap_bytes and implement bootmem_bootmap_pages on top of it. Adjust users of these helpers and make free_all_bootmem_core use bootmem_bootmap_pages instead of open-coding it. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: add debugging frameworkJohannes Weiner2008-07-241-7/+44
| | | | | | | | | | | Introduce the bootmem_debug kernel parameter that enables very verbose diagnostics regarding all range operations of bootmem as well as the initialization and release of nodes. [akpm@linux-foundation.org: fix printk warnings] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: add documentation to API functionsJohannes Weiner2008-07-241-1/+149
| | | | | | Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: clean up bootmem.c file headerJohannes Weiner2008-07-241-9/+5
| | | | | | | | | | Change the description, move a misplaced comment about the allocator itself and add me to the list of copyright holders. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bootmem: reorder code to match new bootmem structureJohannes Weiner2008-07-241-179/+177
| | | | | | | | | This only reorders functions so that further patches will be easier to read. No code changed. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: quota is not freed for unused reserved private huge pagesAdam Litke2008-07-241-1/+3
| | | | | | | | | | | | | | | | | | | | | With shared reservations (and now also with private reservations), we reserve huge pages at mmap time. We also account for the mapping against fs quota to prevent a reservation from being preempted by quota exhaustion. When testing with the libhugetlbfs test suite, I found a problem with quota accounting. FS quota for allocated pages is handled correctly but we are not releasing quota for private pages that were reserved but never allocated. Do this in hugetlb_vm_op_close() at the same time as unused page reservations are released. Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Acked-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: fix a hugepage reservation check for MAP_SHAREDMel Gorman2008-07-241-6/+6
| | | | | | | | | | | | | | | | | | | | | | When removing a huge page from the hugepage pool for a fault the system checks to see if the mapping requires additional pages to be reserved, and if it does whether there are any unreserved pages remaining. If not, the allocation fails without even attempting to get a page. In order to determine whether to apply this check we call vma_has_private_reserves() which tells us if this vma is MAP_PRIVATE and is the owner. This incorrectly triggers the remaining reservation test for MAP_SHARED mappings which prevents allocation of the final page in the pool even though it is reserved for this mapping. In reality we only want to check this for MAP_PRIVATE mappings where the process is not the original mapper. Replace vma_has_private_reserves() with vma_has_reserves() which indicates whether further reserves are required, and update the caller. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: allow arch overridden hugepage allocationJon Tollefson2008-07-241-8/+3
| | | | | | | | | | | | | | | Allow alloc_bootmem_huge_page() to be overridden by architectures that can't always use bootmem. This requires huge_boot_pages to be available for use by this function. This is required for powerpc 16G pages, which have to be reserved prior to boot-time. The location of these pages are indicated in the device tree. Acked-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: override default huge page sizeNick Piggin2008-07-241-6/+17
| | | | | | | | | | | | | | Allow configurations with the default huge page size which is different to the traditional HPAGE_SIZE size. The default huge page size is the one represented in the legacy /proc ABIs, SHM, and which is defaulted to when mounting hugetlbfs filesystems. This is implemented with a new kernel option default_hugepagesz=, which defaults to HPAGE_SIZE if not specified. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: introduce pud_hugeAndi Kleen2008-07-242-4/+20
| | | | | | | | | | | | Straight forward extensions for huge pages located in the PUD instead of PMDs. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: printk cleanupAndi Kleen2008-07-241-4/+16
| | | | | | | | | | | | | - Reword sentence to clarify meaning with multiple options - Add support for using GB prefixes for the page size - Add extra printk to delayed > MAX_ORDER allocation code Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: support boot allocate different sizesAndi Kleen2008-07-241-9/+30
| | | | | | | | | | | | | | | | | | | Make some infrastructure changes to allow boot-time allocation of different hugepage page sizes. - move all basic hstate initialisation into hugetlb_add_hstate - create a new function hugetlb_hstate_alloc_pages() to do the actual initial page allocations. Call this function early in order to allocate giant pages from bootmem. - Check for multiple hugepages= parameters Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Acked-by: Andrew Hastings <abh@cray.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: support larger than MAX_ORDERAndi Kleen2008-07-241-2/+81
| | | | | | | | | | | | | | | | | | | | | | | | | | This is needed on x86-64 to handle GB pages in hugetlbfs, because it is not practical to enlarge MAX_ORDER to 1GB. Instead the 1GB pages are only allocated at boot using the bootmem allocator using the hugepages=... option. These 1G bootmem pages are never freed. In theory it would be possible to implement that with some complications, but since it would be a one-way street (>= MAX_ORDER pages cannot be allocated later) I decided not to currently. The >= MAX_ORDER code is not ifdef'ed per architecture. It is not very big and the ifdef uglyness seemed not be worth it. Known problems: /proc/meminfo and "free" do not display the memory allocated for gb pages in "Total". This is a little confusing for the user. Acked-by: Andrew Hastings <abh@cray.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: export prep_compound_page to mmAndi Kleen2008-07-242-1/+3
| | | | | | | | | | | | hugetlb will need to get compound pages from bootmem to handle the case of them being greater than or equal to MAX_ORDER. Export the constructor function needed for this. Acked-by: Adam Litke <agl@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce non panic alloc_bootmemAndi Kleen2008-07-241-0/+12
| | | | | | | | | | | Straight forward variant of the existing __alloc_bootmem_node, only subsequent patch when allocating giant hugepages at boot -- don't want to panic if we can't allocate as many as the user asked for. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: abstract numa round robin selectionAndi Kleen2008-07-241-15/+22
| | | | | | | | | | | | | Need this as a separate function for a future patch. No behaviour change. Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: new sysfs interfaceNishanth Aravamudan2008-07-241-66/+222
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Provide new hugepages user APIs that are more suited to multiple hstates in sysfs. There is a new directory, /sys/kernel/hugepages. Underneath that directory there will be a directory per-supported hugepage size, e.g.: /sys/kernel/hugepages/hugepages-64kB /sys/kernel/hugepages/hugepages-16384kB /sys/kernel/hugepages/hugepages-16777216kB corresponding to 64k, 16m and 16g respectively. Within each hugepages-size directory there are a number of files, corresponding to the tracked counters in the hstate, e.g.: /sys/kernel/hugepages/hugepages-64/nr_hugepages /sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages /sys/kernel/hugepages/hugepages-64/free_hugepages /sys/kernel/hugepages/hugepages-64/resv_hugepages /sys/kernel/hugepages/hugepages-64/surplus_hugepages Of these files, the first two are read-write and the latter three are read-only. The size of the hugepage being manipulated is trivially deducible from the enclosing directory and is always expressed in kB (to match meminfo). [dave@linux.vnet.ibm.com: fix build] [nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel] [nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency] Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlbfs: per mount huge page sizesAndi Kleen2008-07-242-15/+19
| | | | | | | | | | | | | | | | | | | | | | Add the ability to configure the hugetlb hstate used on a per mount basis. - Add a new pagesize= option to the hugetlbfs mount that allows setting the page size - This option causes the mount code to find the hstate corresponding to the specified size, and sets up a pointer to the hstate in the mount's superblock. - Change the hstate accessors to use this information rather than the global_hstate they were using (requires a slight change in mm/memory.c so we don't NULL deref in the error-unmap path -- see comments). [np: take hstate out of hugetlbfs inode and vma->vm_private_data] Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: multiple hstates for multiple page sizesAndi Kleen2008-07-241-27/+121
| | | | | | | | | | | | | | | | | Add basic support for more than one hstate in hugetlbfs. This is the key to supporting multiple hugetlbfs page sizes at once. - Rather than a single hstate, we now have an array, with an iterator - default_hstate continues to be the struct hstate which we use by default - Add functions for architectures to register new hstates [akpm@linux-foundation.org: coding-style fixes] Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: modular state for hugetlb page sizeAndi Kleen2008-07-244-172/+210
| | | | | | | | | | | | | | | | | | | | | | | | | | The goal of this patchset is to support multiple hugetlb page sizes. This is achieved by introducing a new struct hstate structure, which encapsulates the important hugetlb state and constants (eg. huge page size, number of huge pages currently allocated, etc). The hstate structure is then passed around the code which requires these fields, they will do the right thing regardless of the exact hstate they are operating on. This patch adds the hstate structure, with a single global instance of it (default_hstate), and does the basic work of converting hugetlb to use the hstate. Future patches will add more hstate structures to allow for different hugetlbfs mounts to have different page sizes. [akpm@linux-foundation.org: coding-style fixes] Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: factor out prep_new_huge_pageAndi Kleen2008-07-241-6/+11
| | | | | | | | | | | Needed to avoid code duplication in follow up patches. Acked-by: Adam Litke <agl@us.ibm.com> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: create /sys/kernel/mmNishanth Aravamudan2008-07-241-0/+16
| | | | | | | | | | | | | | | Add a kobject to create /sys/kernel/mm when sysfs is mounted. The kobject will exist regardless. This will allow for the hugepage related sysfs directories to exist under the mm "subsystem" directory. Add an ABI file appropriately. [kosaki.motohiro@jp.fujitsu.com: fix build] Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove mm_init compilation dependency on CONFIG_DEBUG_MEMORY_INITNishanth Aravamudan2008-07-242-2/+3
| | | | | | | | | | | | | | Towards the end of putting all core mm initialization in mm_init.c, I plan on putting the creation of a mm kobject in a function in that file. However, the file is currently only compiled if CONFIG_DEBUG_MEMORY_INIT is set. Remove this dependency, but put the code under an #ifdef on the same config option. This should result in no functional changes. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vmallocinfo: add NUMA informationEric Dumazet2008-07-241-0/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Christoph recently added /proc/vmallocinfo file to get information about vmalloc allocations. This patch adds NUMA specific information, giving number of pages allocated on each memory node. This should help to check that vmalloc() is able to respect NUMA policies. Example of output on a four nodes machine (one cpu per node) 1) network hash tables are evenly spreaded on four nodes (OK) (Same point for inodes and dentries hash tables) 2) iptables tables (x_tables) are correctly allocated on each cpu node (OK). 3) sys_swapon() allocates its memory from one node only. 4) each loaded module is using memory on one node. Sysadmins could tune their setup to change points 3) and 4) if necessary. grep "pages=" /proc/vmallocinfo 0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204/0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128 0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204/0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 0xffffc2000031a000-0xffffc2000031d000 12288 alloc_large_system_hash+0x204/0x2c0 pages=2 vmalloc N1=1 N2=1 0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e/0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3 0xffffc2000033e000-0xffffc20000341000 12288 sys_swapon+0x640/0xac0 pages=2 vmalloc N0=2 0xffffc20000341000-0xffffc20000344000 12288 xt_alloc_table_info+0xfe/0x130 [x_tables] pages=2 vmalloc N0=2 0xffffc20000344000-0xffffc20000347000 12288 xt_alloc_table_info+0xfe/0x130 [x_tables] pages=2 vmalloc N1=2 0xffffc20000347000-0xffffc2000034a000 12288 xt_alloc_table_info+0xfe/0x130 [x_tables] pages=2 vmalloc N2=2 0xffffc2000034a000-0xffffc2000034d000 12288 xt_alloc_table_info+0xfe/0x130 [x_tables] pages=2 vmalloc N3=2 0xffffc20004381000-0xffffc20004402000 528384 alloc_large_system_hash+0x204/0x2c0 pages=128 vmalloc N0=32 N1=32 N2=32 N3=32 0xffffc20004402000-0xffffc20004803000 4198400 alloc_large_system_hash+0x204/0x2c0 pages=1024 vmalloc vpages N0=256 N1=256 N2=256 N3=256 0xffffc20004803000-0xffffc20004904000 1052672 alloc_large_system_hash+0x204/0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64 0xffffc20004904000-0xffffc20004bec000 3047424 sys_swapon+0x640/0xac0 pages=743 vmalloc vpages N0=743 0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 pages=14 vmalloc N1=14 0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 pages=4 vmalloc N0=4 0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 pages=2 vmalloc N0=2 0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 pages=10 vmalloc N1=10 0xffffffffa0022000-0xffffffffa0028000 24576 sys_init_module+0xc27/0x1d00 pages=5 vmalloc N3=5 0xffffffffa0028000-0xffffffffa0050000 163840 sys_init_module+0xc27/0x1d00 pages=39 vmalloc N1=39 0xffffffffa0050000-0xffffffffa0052000 8192 sys_init_module+0xc27/0x1d00 pages=1 vmalloc N1=1 0xffffffffa0052000-0xffffffffa0056000 16384 sys_init_module+0xc27/0x1d00 pages=3 vmalloc N1=3 0xffffffffa0056000-0xffffffffa0081000 176128 sys_init_module+0xc27/0x1d00 pages=42 vmalloc N3=42 0xffffffffa0081000-0xffffffffa00ae000 184320 sys_init_module+0xc27/0x1d00 pages=44 vmalloc N3=44 0xffffffffa00ae000-0xffffffffa00b1000 12288 sys_init_module+0xc27/0x1d00 pages=2 vmalloc N3=2 0xffffffffa00b1000-0xffffffffa00b9000 32768 sys_init_module+0xc27/0x1d00 pages=7 vmalloc N0=7 0xffffffffa00b9000-0xffffffffa00c4000 45056 sys_init_module+0xc27/0x1d00 pages=10 vmalloc N3=10 0xffffffffa00c6000-0xffffffffa00e0000 106496 sys_init_module+0xc27/0x1d00 pages=25 vmalloc N2=25 0xffffffffa00e0000-0xffffffffa00f1000 69632 sys_init_module+0xc27/0x1d00 pages=16 vmalloc N2=16 0xffffffffa00f1000-0xffffffffa00f4000 12288 sys_init_module+0xc27/0x1d00 pages=2 vmalloc N3=2 0xffffffffa00f4000-0xffffffffa00f7000 12288 sys_init_module+0xc27/0x1d00 pages=2 vmalloc N3=2 [akpm@linux-foundation.org: fix comment] Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* tmpfs: support aioHugh Dickins2008-07-241-21/+34
| | | | | | | | | | | | | | | | | | | | | We have a request for tmpfs to support the AIO interface: easily done, no more than replacing the old shmem_file_read by shmem_file_aio_read, cribbed from generic_file_aio_read. (In 2.6.25 its write side was already changed to use generic_file_aio_write.) Incorporate cleanups from Andrew Morton and Harvey Harrison. Tests out fine with LTP's ltp-aiodio.sh, given hacks (not included) to support O_DIRECT. tmpfs cannot honestly support O_DIRECT: its cache-avoiding-IO nature is at odds with direct IO-avoiding-cache. Signed-off-by: Hugh Dickins <hugh@veritas.com> Tested-by: Lawrence Greenfield <leg@google.com> Cc: Christoph Rohland <hans-christoph.rohland@sap.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Zach Brown <zach.brown@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* generic_file_aio_read() cleanupsHugh Dickins2008-07-241-23/+19
| | | | | | | | | | | | | | | | | | | | | As akpm points out, there's really no need for generic_file_aio_read to make a special case of count 0: just loop through nr_segs doing nothing. And as Harvey Harrison points out, there's no need to reset retval to 0 where it's already 0. Setting count (or ocount) to 0 before calling generic_segment_checks is unnecessary too; but reluctantly I'll leave that removal to someone with a wider range of gcc versions to hand - 4.1.2 and 4.2.1 don't warn about it, but perhaps others do - I forget which are the warniest versions. Signed-off-by: Hugh Dickins <hugh@veritas.com> Tested-by: Lawrence Greenfield <leg@google.com> Cc: Christoph Rohland <hans-christoph.rohland@sap.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Zach Brown <zach.brown@oracle.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vma_page_offset() has no callees: drop itJohannes Weiner2008-07-241-20/+9
| | | | | | | | | | | | | | | | | Hugh adds: vma_pagecache_offset() has a dangerously misleading name, since it's using hugepage units: rename it to vma_hugecache_offset(). [apw@shadowen.org: restack onto fixed MAP_PRIVATE reservations] [akpm@linux-foundation.org: vma_split conversion] Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: Adam Litke <agl@us.ibm.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andi Kleen <ak@suse.de> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splitsAndy Whitcroft2008-07-241-27/+145
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a hugetlb mapping with a reservation is split, a new VMA is cloned from the original. This new VMA is a direct copy of the original including the reservation count. When this pair of VMAs are unmapped we will incorrect double account the unused reservation and the overall reservation count will be incorrect, in extreme cases it will wrap. The problem occurs when we split an existing VMA say to unmap a page in the middle. split_vma() will create a new VMA copying all fields from the original. As we are storing our reservation count in vm_private_data this is also copies, endowing the new VMA with a duplicate of the original VMA's reservation. Neither of the new VMAs can exhaust these reservations as they are too small, but when we unmap and close these VMAs we will incorrect credit the remainder twice and resv_huge_pages will become out of sync. This can lead to allocation failures on mappings with reservations and even to resv_huge_pages wrapping which prevents all subsequent hugepage allocations. The simple fix would be to correctly apportion the remaining reservation count when the split is made. However the only hook we have vm_ops->open only has the new VMA we do not know the identity of the preceeding VMA. Also even if we did have that VMA to hand we do not know how much of the reservation was consumed each side of the split. This patch therefore takes a different tack. We know that the whole of any private mapping (which has a reservation) has a reservation over its whole size. Any present pages represent consumed reservation. Therefore if we track the instantiated pages we can calculate the remaining reservation. This patch reuses the existing regions code to track the regions for which we have consumed reservation (ie. the instantiated pages), as each page is faulted in we record the consumption of reservation for the new page. When we need to return unused reservations at unmap time we simply count the consumed reservation region subtracting that from the whole of the map. During a VMA split the newly opened VMA will point to the same region map, as this map is offset oriented it remains valid for both of the split VMAs. This map is referenced counted so that it is removed when all VMAs which are part of the mmap are gone. Thanks to Adam Litke and Mel Gorman for their review feedback. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: allow huge page mappings to be created without reservationsAndy Whitcroft2008-07-241-5/+53
| | | | | | | | | | | | | | | | | | | | | | | | | | By default all shared mappings and most private mappings now have reservations associated with them. This improves semantics by providing allocation guarentees to the mapper. However a small number of applications may attempt to make very large sparse mappings, with these strict reservations the system will never be able to honour the mapping. This patch set brings MAP_NORESERVE support to hugetlb files. This allows new mappings to be made to hugetlbfs files without an associated reservation, for both shared and private mappings. This allows applications which want to create very sparse mappings to opt-out of the reservation system. Obviously as there is no reservation they are liable to fault at runtime if the huge page pool becomes exhausted; buyer beware. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb: move reservation region support earlierAndy Whitcroft2008-07-241-121/+125
| | | | | | | | | | | | | | | | The following patch will require use of the reservation regions support. Move this earlier in the file. No changes have been made to this code. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Acked-by: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: record MAP_NORESERVE status on vmas and fix small page mprotect reservationsAndy Whitcroft2008-07-242-4/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With Mel's hugetlb private reservation support patches applied, strict overcommit semantics are applied to both shared and private huge page mappings. This can be a problem if an application relied on unlimited overcommit semantics for private mappings. An example of this would be an application which maps a huge area with the intention of using it very sparsely. These application would benefit from being able to opt-out of the strict overcommit. It should be noted that prior to hugetlb supporting demand faulting all mappings were fully populated and so applications of this type should be rare. This patch stack implements the MAP_NORESERVE mmap() flag for huge page mappings. This flag has the same meaning as for small page mappings, suppressing reservations for that mapping. Thanks to Mel Gorman for reviewing a number of early versions of these patches. This patch: When a small page mapping is created with mmap() reservations are created by default for any memory pages required. When the region is read/write the reservation is increased for every page, no reservation is needed for read-only regions (as they implicitly share the zero page). Reservations are tracked via the VM_ACCOUNT vma flag which is present when the region has reservation backing it. When we convert a region from read-only to read-write new reservations are aquired and VM_ACCOUNT is set. However, when a read-only map is created with MAP_NORESERVE it is indistinguishable from a normal mapping. When we then convert that to read/write we are forced to incorrectly create reservations for it as we have no record of the original MAP_NORESERVE. This patch introduces a new vma flag VM_NORESERVE which records the presence of the original MAP_NORESERVE flag. This allows us to distinguish these two circumstances and correctly account the reserve. As well as fixing this FIXME in the code, this makes it much easier to introduce MAP_NORESERVE support for huge pages as this flag is available consistantly for the life of the mapping. VM_ACCOUNT on the other hand is heavily used at the generic level in association with small pages. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Adam Litke <agl@us.ibm.com> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Andy Whitcroft <apw@shadowen.org> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generated by cgit v1.1 at 2024-12-26 05:01:13 +0000