- 26 Sep, 2006 40 commits
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Christoph Lameter authored
Profiling really suffers with off node buffers. Fail if no memory is available on the nodes. The profiling code can deal with these failures should they occur. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
There are frequent references to *z in get_page_from_freelist. Add an explicit zone variable that can be used in all these places. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
The uncached allocator manages per node pools. Specify __GFP_THISNODE in order to force allocation on the indicated node or fail. The uncached allocator has already logic to deal with failing allocations. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
If the user specified a node where we should move the page to then we really do not want any other node. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
[PATCH] Add __GFP_THISNODE to avoid fallback to other nodes and ignore cpuset/memory policy restrictions Add a new gfp flag __GFP_THISNODE to avoid fallback to other nodes. This flag is essential if a kernel component requires memory to be located on a certain node. It will be needed for alloc_pages_node() to force allocation on the indicated node and for alloc_pages() to force allocation on the current node. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Ravikiran G Thirumalai authored
Place the alien array cache locks of on slab malloc slab caches on a seperate lockdep class. This avoids false positives from lockdep [akpm@osdl.org: build fix] Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Shai Fultheim <shai@scalex86.org> Cc: Thomas Gleixner <tglx@linutronix.de> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
It is fairly easy to get a system to oops by simply sizing a cache via /proc in such a way that one of the chaches (shared is easiest) becomes bigger than the maximum allowed slab allocation size. This occurs because enable_cpucache() fails if it cannot reallocate some caches. However, enable_cpucache() is used for multiple purposes: resizing caches, cache creation and bootstrap. If the slab is already up then we already have working caches. The resize can fail without a problem. We just need to return the proper error code. F.e. after this patch: # echo "size-64 10000 50 1000" >/proc/slabinfo -bash: echo: write error: Cannot allocate memory notice no OOPS. If we are doing a kmem_cache_create() then we also should not panic but return -ENOMEM. If on the other hand we do not have a fully bootstrapped slab allocator yet then we should indeed panic since we are unable to bring up the slab to its full functionality. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
The ability to free memory allocated to a slab cache is also useful if an error occurs during setup of a slab. So extract the function. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Hellwig authored
[akpm@osdl.org: export fix] Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
Let's try to keep mm/ comments more useful and up to date. This is a start. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Ravikiran G Thirumalai authored
Also, checks if we get a valid slabp_cache for off slab slab-descriptors. We should always get this. If we don't, then in that case we, will have to disable off-slab descriptors for this cache and do the calculations again. This is a rare case, so add a BUG_ON, for now, just in case. Signed-off-by: Alok N Kataria <alok.kataria@calsoftinc.com> Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Shai Fultheim <shai@scalex86.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Heiko Carstens authored
Introduce ARCH_LOW_ADDRESS_LIMIT which can be set per architecture to override the 4GB default limit used by the bootmem allocater within __alloc_bootmem_low() and __alloc_bootmem_low_node(). E.g. s390 needs a 2GB limit instead of 4GB. Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
Print the name of the task invoking the OOM killer. Could make debugging easier. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
Skip kernel threads, rather than having them return 0 from badness. Theoretically, badness might truncate all results to 0, thus a kernel thread might be picked first, causing an infinite loop. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
PF_SWAPOFF processes currently cause select_bad_process to return straight away. Instead, give them high priority, so we will kill them first, however we also first ensure no parallel OOM kills are happening at the same time. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
Having the oomkilladj == OOM_DISABLE check before the releasing check means that oomkilladj == OOM_DISABLE tasks exiting will not stop the OOM killer. Moving the test down will give the desired behaviour. Also: it will allow them to "OOM-kill" themselves if they are exiting. As per the previous patch, this is required to prevent OOM killer deadlocks (and they don't actually get killed, because they're already exiting -- they're simply allowed access to memory reserves). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
If current *is* exiting, it should actually be allowed to access reserved memory rather than OOM kill something else. Can't do this via a straight check in page_alloc.c because that would allow multiple tasks to use up reserves. Instead cause current to OOM-kill itself which will mark it as TIF_MEMDIE. The current procedure of simply aborting the OOM-kill if a task is exiting can lead to OOM deadlocks. In the case of killing a PF_EXITING task, don't make a lot of noise about it. This becomes more important in future patches, where we can "kill" OOM_DISABLE tasks. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
cpuset_excl_nodes_overlap does not always indicate that killing a task will not free any memory we for us. For example, we may be asking for an allocation from _anywhere_ in the machine, or the task in question may be pinning memory that is outside its cpuset. Fix this by just causing cpuset_excl_nodes_overlap to reduce the badness rather than disallow it. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
Potentially it takes several scans of the lru lists before we can even start reclaiming pages. mapped pages, with young ptes can take 2 passes on the active list + one on the inactive list. But reclaim_mapped may not always kick in instantly, so it could take even more than that. Raise the threshold for marking a zone as all_unreclaimable from a factor of 4 time the pages in the zone to 6. Introduce a mechanism to force reclaim_mapped if we've reached a factor 3 and still haven't made progress. Previously, a customer doing stress testing was able to easily OOM the box after using only a small fraction of its swap (~100MB). After the patches, it would only OOM after having used up all swap (~800MB). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
__alloc_pages currently starts shooting if page reclaim has failed to free up swap_cluster_max pages in one run through the priorities. This is not always a good indicator on its own, so make use of the all_unreclaimable logic as well: don't consider going OOM until all zones we're interested in are unreclaimable. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Peter Zijlstra authored
Currently we can silently drop data if the write to swap failed. It usually doesn't result in data-corruption because on page-in the process will receive SIGBUS (assuming write-failure implies read-failure). This assumption might or might not be valid. This patch will avoid the page being discarded after a failed write. But will print a warning the sysadmin _should_ take to heart, if a lot of swap space becomes un-writeable, OOM is not far off. Tested by making the write fail 'randomly' once every 50 writes or so. [akpm@osdl.org: printk warning fix] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Pekka Enberg authored
As explained by Heiko, on s390 (32-bit) ARCH_KMALLOC_MINALIGN is set to eight because their common I/O layer allocates data structures that need to have an eight byte alignment. This does not work when CONFIG_SLAB_DEBUG is enabled because kmem_cache_create will override alignment to BYTES_PER_WORD which is four. So change kmem_cache_create to ensure cache alignment is always at minimum what the architecture or caller mandates even if slab debugging is enabled. Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
lock_page needs the caller to have a reference on the page->mapping inode due to sync_page, ergo set_page_dirty_lock is obviously buggy according to its comments. Solve it by introducing a new lock_page_nosync which does not do a sync_page. akpm: unpleasant solution to an unpleasant problem. If it goes wrong it could cause great slowdowns while the lock_page() caller waits for kblockd to perform the unplug. And if a filesystem has special sync_page() requirements (none presently do), permanent hangs are possible. otoh, set_page_dirty_lock() is usually (always?) called against userspace pages. They are always up-to-date, so there shouldn't be any pending read I/O against these pages. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored
Some users of remove_mapping had been unsafe. Modify the remove_mapping precondition to ensure the caller has locked the page and obtained the correct mapping. Modify callers to ensure the mapping is the correct one. [hugh@veritas.com: swapper_space fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Rolf Eike Beer authored
These functions are already documented quite well with long comments. Now add kerneldoc style header to make this turn up in everyones favorite doc format. Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Martin Peschke authored
This patch splits alloc_percpu() up into two phases. Likewise for free_percpu(). This allows clients to limit initial allocations to online cpu's, and to populate or depopulate per-cpu data at run time as needed: struct my_struct *obj; /* initial allocation for online cpu's */ obj = percpu_alloc(sizeof(struct my_struct), GFP_KERNEL); ... /* populate per-cpu data for cpu coming online */ ptr = percpu_populate(obj, sizeof(struct my_struct), GFP_KERNEL, cpu); ... /* access per-cpu object */ ptr = percpu_ptr(obj, smp_processor_id()); ... /* depopulate per-cpu data for cpu going offline */ percpu_depopulate(obj, cpu); ... /* final removal */ percpu_free(obj); Signed-off-by: Martin Peschke <mp3@de.ibm.com> Cc: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Martin Schwidefsky authored
Add a notifer chain to the out of memory killer. If one of the registered callbacks could release some memory, do not kill the process but return and retry the allocation that forced the oom killer to run. The purpose of the notifier is to add a safety net in the presence of memory ballooners. If the resource manager inflated the balloon to a size where memory allocations can not be satisfied anymore, it is better to deflate the balloon a bit instead of killing processes. The implementation for the s390 ballooner is included. [akpm@osdl.org: cleanups] Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
I wonder why we need this bitmask indexing into zone->node_zonelists[]? We always start with the highest zone and then include all lower zones if we build zonelists. Are there really cases where we need allocation from ZONE_DMA or ZONE_HIGHMEM but not ZONE_NORMAL? It seems that the current implementation of highest_zone() makes that already impossible. If we go linear on the index then gfp_zone() == highest_zone() and a lot of definitions fall by the wayside. We can now revert back to the use of gfp_zone() in mempolicy.c ;-) Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
After we have done this we can now do some typing cleanup. The memory policy layer keeps a policy_zone that specifies the zone that gets memory policies applied. This variable can now be of type enum zone_type. The check_highest_zone function and the build_zonelists funnctionm must then also take a enum zone_type parameter. Plus there are a number of loops over zones that also should use zone_type. We run into some troubles at some points with functions that need a zone_type variable to become -1. Fix that up. [pj@sgi.com: fix set_mempolicy() crash] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
There is a check in zonelist_policy that compares pieces of the bitmap obtained from a gfp mask via GFP_ZONETYPES with a zone number in function zonelist_policy(). The bitmap is an ORed mask of __GFP_DMA, __GFP_DMA32 and __GFP_HIGHMEM. The policy_zone is a zone number with the possible values of ZONE_DMA, ZONE_DMA32, ZONE_HIGHMEM and ZONE_NORMAL. These are two different domains of values. For some reason seemed to work before the zone reduction patchset (It definitely works on SGI boxes since we just have one zone and the check cannot fail). With the zone reduction patchset this check definitely fails on systems with two zones if the system actually has memory in both zones. This is because ZONE_NORMAL is selected using no __GFP flag at all and thus gfp_zone(gfpmask) == 0. ZONE_DMA is selected when __GFP_DMA is set. __GFP_DMA is 0x01. So gfp_zone(gfpmask) == 1. policy_zone is set to ZONE_NORMAL (==1) if ZONE_NORMAL and ZONE_DMA are populated. For ZONE_NORMAL gfp_zone(<no _GFP_DMA>) yields 0 which is < policy_zone(ZONE_NORMAL) and so policy is not applied to regular memory allocations! Instead gfp_zone(__GFP_DMA) == 1 which results in policy being applied to DMA allocations! What we realy want in that place is to establish the highest allowable zone for a given gfp_mask. If the highest zone is higher or equal to the policy_zone then memory policies need to be applied. We have such a highest_zone() function in page_alloc.c. So move the highest_zone() function from mm/page_alloc.c into include/linux/gfp.h. On the way we simplify the function and use the new zone_type that was also introduced with the zone reduction patchset plus we also specify the right type for the gfp flags parameter. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
We cannot check MAX_NR_ZONES since it not defined in the preprocessor anymore. So remove the check. The maximum number of zones per node for i386 is 3 since i386 does not support ZONE_DMA32. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
eventcounters: Do not display counters for zones that are not available on an arch Do not define or display counters for the DMA32 and the HIGHMEM zone if such zones were not configured. [akpm@osdl.org: s390 fix] [heiko.carstens@de.ibm.com: s390 fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
Make ZONE_HIGHMEM optional - ifdef out code and definitions related to CONFIG_HIGHMEM - __GFP_HIGHMEM falls back to normal allocations if there is no ZONE_HIGHMEM - GFP_ZONEMASK becomes 0x01 if there is no DMA32 and no HIGHMEM zone. [jdike@addtoit.com: build fix] Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
Make ZONE_DMA32 optional - Add #ifdefs around ZONE_DMA32 specific code and definitions. - Add CONFIG_ZONE_DMA32 config option and use that for x86_64 that alone needs this zone. - Remove the use of CONFIG_DMA_IS_DMA32 and CONFIG_DMA_IS_NORMAL for ia64 and fix up the way per node ZVCs are calculated. - Fall back to prior GFP_ZONEMASK of 0x03 if there is no DMA32 zone. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
Use enum for zones and reformat zones dependent information Add comments explaning the use of zones and add a zones_t type for zone numbers. Line up information that will be #ifdefd by the following patches. [akpm@osdl.org: comment cleanups] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
page allocator ZONE_HIGHMEM fixups 1. We do not need to do an #ifdef in si_meminfo since both counters in use are zero if !CONFIG_HIGHMEM. 2. Add #ifdef in si_meminfo_node instead to avoid referencing zone information for ZONE_HIGHMEM if we do not have HIGHMEM (may not be there after the following patches). 3. Replace the use of ZONE_HIGHMEM with MAX_NR_ZONES in build_zonelists_node 4. build_zonelists_node: Remove BUG_ON for ZONE_HIGHMEM. Zone will be optional soon and thus BUG_ON cannot be triggered anymore. 5. init_free_area_core: Replace a use of ZONE_HIGHMEM with NR_MAX_ZONES. [akpm@osdl.org: cleanups] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
Move totalhigh_pages and nr_free_highpages() into highmem.c/.h Move the totalhigh_pages definition into highmem.c/.h. Move the nr_free_highpages function into highmem.c [yoichi_yuasa@tripeaks.co.jp: build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
Do not display HIGHMEM memory sizes if CONFIG_HIGHMEM is not set. Make HIGHMEM dependent texts and make display of highmem counters optional Some texts are depending on CONFIG_HIGHMEM. Remove those strings and remove the display of highmem counter values if CONFIG_HIGHMEM is not set. [akpm@osdl.org: remove some ifdefs] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
Fix array initialization in lots of arches The number of zones may now be reduced from 4 to 2 for many arches. Fix the array initialization for the zones array for all architectures so that it is not initializing a fixed number of elements. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
I keep seeing zones on various platforms that are never used and wonder why we compile support for them into the kernel. Counters show up for HIGHMEM and DMA32 that are alway zero. This patch allows the removal of ZONE_DMA32 for non x86_64 architectures and it will get rid of ZONE_HIGHMEM for arches not using highmem (like 64 bit architectures). If an arch does not define CONFIG_HIGHMEM then ZONE_HIGHMEM will not be defined. Similarly if an arch does not define CONFIG_ZONE_DMA32 then ZONE_DMA32 will not be defined. No current architecture uses all the 4 zones (DMA,DMA32,NORMAL,HIGH) that we have now. The patchset will reduce the number of zones for all platforms. On many platforms that do not have DMA32 or HIGHMEM this will reduce the number of zones by 50%. F.e. ia64 only uses DMA and NORMAL. Large amounts of memory can be saved for larger systemss that may have a few hundred NUMA nodes. With ZONE_DMA32 and ZONE_HIGHMEM support optional MAX_NR_ZONES will be 2 for many non i386 platforms and even for i386 without CONFIG_HIGHMEM set. Tested on ia64, x86_64 and on i386 with and without highmem. The patchset consists of 11 patches that are following this message. One could go even further than this patchset and also make ZONE_DMA optional because some platforms do not need a separate DMA zone and can do DMA to all of memory. This could reduce MAX_NR_ZONES to 1. Such a patchset will hopefully follow soon. This patch: Fix strange uses of MAX_NR_ZONES Sometimes we use MAX_NR_ZONES - x to refer to a zone. Make that explicit. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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