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2009-10-29percpu: allow pcpu_alloc() to be called with IRQs offJiri Kosina
pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Tejun Heo <tj@kernel.org>
2009-10-12percpu: fix compile warningsTejun Heo
Fix the following two compile warnings which show up on i386. mm/percpu.c:1873: warning: comparison of distinct pointer types lacks a cast mm/percpu.c:1879: warning: format '%lx' expects type 'long unsigned int', but argument 2 has type 'size_t' Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
2009-09-29percpu: make allocation failures more verboseTejun Heo
Warn and dump stack when percpu allocation fails. percpu allocator is still young and unchecked NULL percpu pointer usage can result in random memory corruption when combined with the pointer shifting in access macros. Allocation failures should be rare and the warning message will be disabled after certain times. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-09-29percpu: make pcpu_setup_first_chunk() failures more verboseTejun Heo
The parameters to pcpu_setup_first_chunk() come from different sources depending on architecture and can be quite complex. The function runs various sanity checks on the parameters and triggers BUG() if something isn't right. However, this is very early during the boot and not reporting exactly what the problem is makes debugging even harder. Add PCPU_SETUP_BUG() macro which prints out enough information about the parameters. As the macro still puts separate BUG() for each check, it won't lose any information even on the situations where only the program counter can be retrieved. While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so that it's visible on the console if boot fails to complete. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-09-29percpu: make embedding first chunk allocator check vmalloc space sizeTejun Heo
Embedding first chunk allocator maintains the distances between units in the vmalloc area and thus needs vmalloc space to be larger than the maximum distances between units; otherwise, it wouldn't be able to create any dynamic chunks. This patch makes the embedding first chunk allocator check vmalloc space size and if the maximum distance between units is larger than 75% of it, print warning and, if page mapping allocator is available, fail initialization so that the system falls back onto it. This should work around percpu allocation failure problems on certain sparc64 configurations where distances between NUMA nodes are larger than the vmalloc area and makes percpu allocator more robust for future configurations. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-09-29percpu: make pcpu_build_alloc_info() clear static buffersTejun Heo
pcpu_build_alloc_info() may be called multiple times when percpu is falling back to different first chunk allocator. Make it clear static buffers so that they don't contain values from previous runs. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-09-29percpu: fix unit_map[] verification in pcpu_setup_first_chunk()Tejun Heo
pcpu_setup_first_chunk() incorrectly used NR_CPUS as the impossible unit number while unit number can equal and go over NR_CPUS with sparse unit map. This triggers BUG_ON() spuriously on machines which have non-power-of-two number of cpus. Use UINT_MAX instead. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Tony Vroon <tony@linx.net>
2009-09-15Merge branch 'for-next' into for-linusTejun Heo
* pcpu_chunk_page_occupied() doesn't exist in for-next. * pcpu_chunk_addr_search() updated to use raw_smp_processor_id(). Conflicts: mm/percpu.c
2009-09-01percpu: don't assume existence of cpu0Tejun Heo
percpu incorrectly assumed that cpu0 was always there which led to the following warning and eventual oops on sparc machines w/o cpu0. WARNING: at mm/percpu.c:651 pcpu_map+0xdc/0x100() Modules linked in: Call Trace: [000000000045eb70] warn_slowpath_common+0x50/0xa0 [000000000045ebdc] warn_slowpath_null+0x1c/0x40 [00000000004d493c] pcpu_map+0xdc/0x100 [00000000004d59a4] pcpu_alloc+0x3e4/0x4e0 [00000000004d5af8] __alloc_percpu+0x18/0x40 [00000000005b112c] __percpu_counter_init+0x4c/0xc0 ... Unable to handle kernel NULL pointer dereference ... I7: <sysfs_new_dirent+0x30/0x120> Disabling lock debugging due to kernel taint Caller[000000000053c1b0]: sysfs_new_dirent+0x30/0x120 Caller[000000000053c7a4]: create_dir+0x24/0xc0 Caller[000000000053c870]: sysfs_create_dir+0x30/0x80 Caller[00000000005990e8]: kobject_add_internal+0xc8/0x200 ... Kernel panic - not syncing: Attempted to kill the idle task! This patch fixes the problem by backporting parts from devel branch to make percpu core not depend on the existence of cpu0. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Meelis Roos <mroos@linux.ee> Cc: David Miller <davem@davemloft.net>
2009-08-14percpu: kill lpage first chunk allocatorTejun Heo
With x86 converted to embedding allocator, lpage doesn't have any user left. Kill it along with cpa handling code. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jan Beulich <JBeulich@novell.com>
2009-08-14percpu: update embedding first chunk allocator to handle sparse unitsTejun Heo
Now that percpu core can handle very sparse units, given that vmalloc space is large enough, embedding first chunk allocator can use any memory to build the first chunk. This patch teaches pcpu_embed_first_chunk() about distances between cpus and to use alloc/free callbacks to allocate node specific areas for each group and use them for the first chunk. This brings the benefits of embedding allocator to NUMA configurations - no extra TLB pressure with the flexibility of unified dynamic allocator and no need to restructure arch code to build memory layout suitable for percpu. With units put into atom_size aligned groups according to cpu distances, using large page for dynamic chunks is also easily possible with falling back to reuglar pages if large allocation fails. Embedding allocator users are converted to specify NULL cpu_distance_fn, so this patch doesn't cause any visible behavior difference. Following patches will convert them. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: use group information to allocate vmap areas sparselyTejun Heo
ai->groups[] contains which units need to be put consecutively and at what offset from the chunk base address. Compile this information into pcpu_group_offsets[] and pcpu_group_sizes[] in pcpu_setup_first_chunk() and use them to allocate sparse vm areas using pcpu_get_vm_areas(). This will be used to allow directly using sparse NUMA memories as percpu areas. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de>
2009-08-14percpu: add chunk->base_addrTejun Heo
The only thing percpu allocator wants to know about a vmalloc area is the base address. Instead of requiring chunk->vm, add chunk->base_addr which contains the necessary value. This simplifies the code a bit and makes the dummy first_vm unnecessary. This change will ease allowing a chunk to be mapped by multiple vms. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: add pcpu_unit_offsets[]Tejun Heo
Currently units are mapped sequentially into address space. This patch adds pcpu_unit_offsets[] which allows units to be mapped to arbitrary offsets from the chunk base address. This is necessary to allow sparse embedding which might would need to allocate address ranges and memory areas which aren't aligned to unit size but allocation atom size (page or large page size). This also simplifies things a bit by removing the need to calculate offset from unit number. With this change, there's no need for the arch code to know pcpu_unit_size. Update pcpu_setup_first_chunk() and first chunk allocators to return regular 0 or -errno return code instead of unit size or -errno. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David S. Miller <davem@davemloft.net>
2009-08-14percpu: introduce pcpu_alloc_info and pcpu_group_infoTejun Heo
Till now, non-linear cpu->unit map was expressed using an integer array which maps each cpu to a unit and used only by lpage allocator. Although how many units have been placed in a single contiguos area (group) is known while building unit_map, the information is lost when the result is recorded into the unit_map array. For lpage allocator, as all allocations are done by lpages and whether two adjacent lpages are in the same group or not is irrelevant, this didn't cause any problem. Non-linear cpu->unit mapping will be used for sparse embedding and this grouping information is necessary for that. This patch introduces pcpu_alloc_info which contains all the information necessary for initializing percpu allocator. pcpu_alloc_info contains array of pcpu_group_info which describes how units are grouped and mapped to cpus. pcpu_group_info also has base_offset field to specify its offset from the chunk's base address. pcpu_build_alloc_info() initializes this field as if all groups are allocated back-to-back as is currently done but this will be used to sparsely place groups. pcpu_alloc_info is a rather complex data structure which contains a flexible array which in turn points to nested cpu_map arrays. * pcpu_alloc_alloc_info() and pcpu_free_alloc_info() are provided to help dealing with pcpu_alloc_info. * pcpu_lpage_build_unit_map() is updated to build pcpu_alloc_info, generalized and renamed to pcpu_build_alloc_info(). @cpu_distance_fn may be NULL indicating that all cpus are of LOCAL_DISTANCE. * pcpul_lpage_dump_cfg() is updated to process pcpu_alloc_info, generalized and renamed to pcpu_dump_alloc_info(). It now also prints which group each alloc unit belongs to. * pcpu_setup_first_chunk() now takes pcpu_alloc_info instead of the separate parameters. All first chunk allocators are updated to use pcpu_build_alloc_info() to build alloc_info and call pcpu_setup_first_chunk() with it. This has the side effect of packing units for sparse possible cpus. ie. if cpus 0, 2 and 4 are possible, they'll be assigned unit 0, 1 and 2 instead of 0, 2 and 4. * x86 setup_pcpu_lpage() is updated to deal with alloc_info. * sparc64 setup_per_cpu_areas() is updated to build alloc_info. Although the changes made by this patch are pretty pervasive, it doesn't cause any behavior difference other than packing of sparse cpus. It mostly changes how information is passed among initialization functions and makes room for more flexibility. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>
2009-08-14percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upwardTejun Heo
Unit map handling will be generalized and extended and used for embedding sparse first chunk and other purposes. Relocate two unit_map related functions upward in preparation. This patch just moves the code without any actual change. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: add @align to pcpu_fc_alloc_fn_tTejun Heo
pcpu_fc_alloc_fn_t is about to see more interesting usage, add @align parameter. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: make @dyn_size mandatory for pcpu_setup_first_chunk()Tejun Heo
Now that all actual first chunk allocation and copying happen in the first chunk allocators and helpers, there's no reason for pcpu_setup_first_chunk() to try to determine @dyn_size automatically. The only left user is page first chunk allocator. Make it determine dyn_size like other allocators and make @dyn_size mandatory for pcpu_setup_first_chunk(). Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: drop @static_size from first chunk allocatorsTejun Heo
First chunk allocators assume percpu areas have been linked using one of PERCPU_*() macros and depend on __per_cpu_load symbol defined by those macros, so there isn't much point in passing in static area size explicitly when it can be easily calculated from __per_cpu_start and __per_cpu_end. Drop @static_size from all percpu first chunk allocators and helpers. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: generalize first chunk allocator selectionTejun Heo
Now that all first chunk allocators are in mm/percpu.c, it makes sense to make generalize percpu_alloc kernel parameter. Define PCPU_FC_* and set pcpu_chosen_fc using early_param() in mm/percpu.c. Arch code can use the set value to determine which first chunk allocator to use. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: build first chunk allocators selectivelyTejun Heo
There's no need to build unused first chunk allocators in. Define CONFIG_NEED_PER_CPU_*_FIRST_CHUNK and let archs enable them selectively. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: rename 4k first chunk allocator to pageTejun Heo
Page size isn't always 4k depending on arch and configuration. Rename 4k first chunk allocator to page. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: David Howells <dhowells@redhat.com>
2009-08-14percpu: improve boot messagesTejun Heo
Improve percpu boot messages such that they're uniform and contain more information. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
2009-08-14percpu: fix pcpu_reclaim() lockingTejun Heo
pcpu_reclaim() calls pcpu_depopulate_chunk() which makes use of pages array and bitmap returned by pcpu_get_pages_and_bitmap() and thus should be called under pcpu_alloc_mutex. pcpu_reclaim() released the mutex before calling depopulate leading to double free and other strange problems caused by the unexpected concurrent usages of pages array and bitmap. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
2009-08-14Merge branch 'percpu-for-linus' into percpu-for-nextTejun Heo
Conflicts: arch/sparc/kernel/smp_64.c arch/x86/kernel/cpu/perf_counter.c arch/x86/kernel/setup_percpu.c drivers/cpufreq/cpufreq_ondemand.c mm/percpu.c Conflicts in core and arch percpu codes are mostly from commit ed78e1e078dd44249f88b1dd8c76dafb39567161 which substituted many num_possible_cpus() with nr_cpu_ids. As for-next branch has moved all the first chunk allocators into mm/percpu.c, the changes are moved from arch code to mm/percpu.c. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-08-14percpu: use the right flag for get_vm_area()Amerigo Wang
get_vm_area() only accepts VM_* flags, not GFP_*. And according to the doc of get_vm_area(), here should be VM_ALLOC. Signed-off-by: WANG Cong <amwang@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-08-14percpu, sparc64: fix sparse possible cpu map handlingTejun Heo
percpu code has been assuming num_possible_cpus() == nr_cpu_ids which is incorrect if cpu_possible_map contains holes. This causes percpu code to access beyond allocated memories and vmalloc areas. On a sparc64 machine with cpus 0 and 2 (u60), this triggers the following warning or fails boot. WARNING: at /devel/tj/os/work/mm/vmalloc.c:106 vmap_page_range_noflush+0x1f0/0x240() Modules linked in: Call Trace: [00000000004b17d0] vmap_page_range_noflush+0x1f0/0x240 [00000000004b1840] map_vm_area+0x20/0x60 [00000000004b1950] __vmalloc_area_node+0xd0/0x160 [0000000000593434] deflate_init+0x14/0xe0 [0000000000583b94] __crypto_alloc_tfm+0xd4/0x1e0 [00000000005844f0] crypto_alloc_base+0x50/0xa0 [000000000058b898] alg_test_comp+0x18/0x80 [000000000058dad4] alg_test+0x54/0x180 [000000000058af00] cryptomgr_test+0x40/0x60 [0000000000473098] kthread+0x58/0x80 [000000000042b590] kernel_thread+0x30/0x60 [0000000000472fd0] kthreadd+0xf0/0x160 ---[ end trace 429b268a213317ba ]--- This patch fixes generic percpu functions and sparc64 setup_per_cpu_areas() so that they handle sparse cpu_possible_map properly. Please note that on x86, cpu_possible_map() doesn't contain holes and thus num_possible_cpus() == nr_cpu_ids and this patch doesn't cause any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: David S. Miller <davem@davemloft.net> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04percpu: teach large page allocator about NUMATejun Heo
Large page first chunk allocator is primarily used for NUMA machines; however, its NUMA handling is extremely simplistic. Regardless of their proximity, each cpu is put into separate large page just to return most of the allocated space back wasting large amount of vmalloc space and increasing cache footprint. This patch teachs NUMA details to large page allocator. Given processor proximity information, pcpu_lpage_build_unit_map() will find fitting cpu -> unit mapping in which cpus in LOCAL_DISTANCE share the same large page and not too much virtual address space is wasted. This greatly reduces the unit and thus chunk size and wastes much less address space for the first chunk. For example, on 4/4 NUMA machine, the original code occupied 16MB of virtual space for the first chunk while the new code only uses 4MB - one 2MB page for each node. [ Impact: much better space efficiency on NUMA machines ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jan Beulich <JBeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: David Miller <davem@davemloft.net>
2009-07-04percpu: allow non-linear / sparse cpu -> unit mappingTejun Heo
Currently cpu and unit are always identity mapped. To allow more efficient large page support on NUMA and lazy allocation for possible but offline cpus, cpu -> unit mapping needs to be non-linear and/or sparse. This can be easily implemented by adding a cpu -> unit mapping array and using it whenever looking up the matching unit for a cpu. The only unusal conversion is in pcpu_chunk_addr_search(). The passed in address is unit0 based and unit0 might not be in use so it needs to be converted to address of an in-use unit. This is easily done by adding the unit offset for the current processor. [ Impact: allows non-linear/sparse cpu -> unit mapping, no visible change yet ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>
2009-07-04percpu: drop pcpu_chunk->page[]Tejun Heo
percpu core doesn't need to tack all the allocated pages. It needs to know whether certain pages are populated and a way to reverse map address to page when freeing. This patch drops pcpu_chunk->page[] and use populated bitmap and vmalloc_to_page() lookup instead. Using vmalloc_to_page() exclusively is also possible but complicates first chunk handling, inflates cache footprint and prevents non-standard memory allocation for percpu memory. pcpu_chunk->page[] was used to track each page's allocation and allowed asymmetric population which happens during failure path; however, with single bitmap for all units, this is no longer possible. Bite the bullet and rewrite (de)populate functions so that things are done in clearly separated steps such that asymmetric population doesn't happen. This makes the (de)population process much more modular and will also ease implementing non-standard memory usage in the future (e.g. large pages). This makes @get_page_fn parameter to pcpu_setup_first_chunk() unnecessary. The parameter is dropped and all first chunk helpers are updated accordingly. Please note that despite the volume most changes to first chunk helpers are symbol renames for variables which don't need to be referenced outside of the helper anymore. This change reduces memory usage and cache footprint of pcpu_chunk. Now only #unit_pages bits are necessary per chunk. [ Impact: reduced memory usage and cache footprint for bookkeeping ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net>
2009-07-04percpu: reorder a few functions in mm/percpu.cTejun Heo
(de)populate functions are about to be reimplemented to drop pcpu_chunk->page array. Move a few functions so that the rewrite patch doesn't have code movement making it more difficult to read. [ Impact: code movement ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04percpu: simplify pcpu_setup_first_chunk()Tejun Heo
Now that all first chunk allocator helpers allocate and map the first chunk themselves, there's no need to have optional default alloc/map in pcpu_setup_first_chunk(). Drop @populate_pte_fn and only leave @dyn_size optional and make all other params mandatory. This makes it much easier to follow what pcpu_setup_first_chunk() is doing and what actual differences tweaking each parameter results in. [ Impact: drop unused code path ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04x86,percpu: generalize lpage first chunk allocatorTejun Heo
Generalize and move x86 setup_pcpu_lpage() into pcpu_lpage_first_chunk(). setup_pcpu_lpage() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free/map memory, pcpu_lpage_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, factor out pcpu_calc_fc_sizes() which is common to pcpu_embed_first_chunk() and pcpu_lpage_first_chunk(). [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04percpu: make 4k first chunk allocator map memoryTejun Heo
At first, percpu first chunk was always setup page-by-page by the generic code. To add other allocators, different parts of the generic initialization was made optional. Now we have three allocators - embed, remap and 4k. embed and remap fully handle allocation and mapping of the first chunk while 4k still depends on generic code for those. This makes the generic alloc/map paths specifci to 4k and makes the code unnecessary complicated with optional generic behaviors. This patch makes the 4k allocator to allocate and map memory directly instead of depending on the generic code. The only outside visible change is that now dynamic area in the first chunk is allocated up-front instead of on-demand. This doesn't make any meaningful difference as the area is minimal (usually less than a page, just enough to fill the alignment) on 4k allocator. Plus, dynamic area in the first chunk usually gets fully used anyway. This will allow simplification of pcpu_setpu_first_chunk() and removal of chunk->page array. [ Impact: no outside visible change other than up-front allocation of dyn area ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04x86,percpu: generalize 4k first chunk allocatorTejun Heo
Generalize and move x86 setup_pcpu_4k() into pcpu_4k_first_chunk(). setup_pcpu_4k() now is a simple wrapper around the generalized version. Other than taking size parameters and using arch supplied callbacks to allocate/free memory, pcpu_4k_first_chunk() is identical to the original implementation. This simplifies arch code and will help converting more archs to dynamic percpu allocator. While at it, s/pcpu_populate_pte_fn_t/pcpu_fc_populate_pte_fn_t/ for consistency. [ Impact: code reorganization and generalization ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04percpu: drop @unit_size from embed first chunk allocatorTejun Heo
The only extra feature @unit_size provides is making dead space at the end of the first chunk which doesn't have any valid usecase. Drop the parameter. This will increase consistency with generalized 4k allocator. James Bottomley spotted missing conversion for the default setup_per_cpu_areas() which caused build breakage on all arcsh which use it. [ Impact: drop unused code path ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Ingo Molnar <mingo@elte.hu>
2009-07-04x86: make pcpu_chunk_addr_search() matching stricterTejun Heo
The @addr passed into pcpu_chunk_addr_search() is unit0 based address and thus should be matched inside unit0 area. Currently, when it uses chunk size when determining whether the address falls in the first chunk. Addresses in unitN where N>0 shouldn't be passed in anyway, so this doesn't cause any malfunction but fix it for consistency. [ Impact: mostly cleanup ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-06-24percpu: use dynamic percpu allocator as the default percpu allocatorTejun Heo
This patch makes most !CONFIG_HAVE_SETUP_PER_CPU_AREA archs use dynamic percpu allocator. The first chunk is allocated using embedding helper and 8k is reserved for modules. This ensures that the new allocator behaves almost identically to the original allocator as long as static percpu variables are concerned, so it shouldn't introduce much breakage. s390 and alpha use custom SHIFT_PERCPU_PTR() to work around addressing range limit the addressing model imposes. Unfortunately, this breaks if the address is specified using a variable, so for now, the two archs aren't converted. The following architectures are affected by this change. * sh * arm * cris * mips * sparc(32) * blackfin * avr32 * parisc (broken, under investigation) * m32r * powerpc(32) As this change makes the dynamic allocator the default one, CONFIG_HAVE_DYNAMIC_PER_CPU_AREA is replaced with its invert - CONFIG_HAVE_LEGACY_PER_CPU_AREA, which is added to yet-to-be converted archs. These archs implement their own setup_per_cpu_areas() and the conversion is not trivial. * powerpc(64) * sparc(64) * ia64 * alpha * s390 Boot and batch alloc/free tests on x86_32 with debug code (x86_32 doesn't use default first chunk initialization). Compile tested on sparc(32), powerpc(32), arm and alpha. Kyle McMartin reported that this change breaks parisc. The problem is still under investigation and he is okay with pushing this patch forward and fixing parisc later. [ Impact: use dynamic allocator for most archs w/o custom percpu setup ] Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Reviewed-by: Christoph Lameter <cl@linux.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mikael Starvik <starvik@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Bryan Wu <cooloney@kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Grant Grundler <grundler@parisc-linux.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu>
2009-06-22x86: implement percpu_alloc kernel parameterTejun Heo
According to Andi, it isn't clear whether lpage allocator is worth the trouble as there are many processors where PMD TLB is far scarcer than PTE TLB. The advantage or disadvantage probably depends on the actual size of percpu area and specific processor. As performance degradation due to TLB pressure tends to be highly workload specific and subtle, it is difficult to decide which way to go without more data. This patch implements percpu_alloc kernel parameter to allow selecting which first chunk allocator to use to ease debugging and testing. While at it, make sure all the failure paths report why something failed to help determining why certain allocator isn't working. Also, kill the "Great future plan" comment which had already been realized quite some time ago. [ Impact: allow explicit percpu first chunk allocator selection ] Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jan Beulich <JBeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu>
2009-06-22percpu: fix too lazy vunmap cache flushingTejun Heo
In pcpu_unmap(), flushing virtual cache on vunmap can't be delayed as the page is going to be returned to the page allocator. Only TLB flushing can be put off such that vmalloc code can handle it lazily. Fix it. [ Impact: fix subtle virtual cache flush bug ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu>
2009-04-08percpu: remove rbtree and use page->index insteadChristoph Lameter
Impact: use page->index for addr to chunk mapping instead of dedicated rbtree The rbtree is used to determine the chunk from the virtual address. However, we can already determine the page struct from a virtual address and there are several unused fields in page struct used by vmalloc. Use the index field to store a pointer to the chunk. Then there is no need anymore for an rbtree. tj: * s/(set|get)_chunk/pcpu_\1_page_chunk/ * Drop inline from the above two functions and moved them upwards so that they are with other simple helpers. * Initial pages might not (actually most of the time don't) live in the vmalloc area. With the previous patch to manually reverse-map both first chunks, this is no longer an issue. Removed pcpu_set_chunk() call on initial pages. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: rusty@rustcorp.com.au Cc: Paul Mundt <lethal@linux-sh.org> Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: ralf@linux-mips.org Cc: davem@davemloft.net Cc: cooloney@kernel.org Cc: kyle@mcmartin.ca Cc: matthew@wil.cx Cc: grundler@parisc-linux.org Cc: takata@linux-m32r.org Cc: benh@kernel.crashing.org Cc: rth@twiddle.net Cc: ink@jurassic.park.msu.ru Cc: heiko.carstens@de.ibm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> LKML-Reference: <49D43D58.4050102@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-08percpu: don't put the first chunk in reverse-map rbtreeTejun Heo
Impact: both first chunks don't use rbtree, no functional change There can be two first chunks - reserved and dynamic with the former one being optional. Dynamic first chunk was linked on reverse-mapping rbtree while the reserved one was mapped manually using the start address and reserved offset limit. This patch makes both first chunks to be looked up manually without using the rbtree. This is to help getting rid of the rbtree. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: rusty@rustcorp.com.au Cc: Paul Mundt <lethal@linux-sh.org> Cc: rmk@arm.linux.org.uk Cc: starvik@axis.com Cc: ralf@linux-mips.org Cc: davem@davemloft.net Cc: cooloney@kernel.org Cc: kyle@mcmartin.ca Cc: matthew@wil.cx Cc: grundler@parisc-linux.org Cc: takata@linux-m32r.org Cc: benh@kernel.crashing.org Cc: rth@twiddle.net Cc: ink@jurassic.park.msu.ru Cc: heiko.carstens@de.ibm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nick Piggin <npiggin@suse.de> Cc: Christoph Lameter <cl@linux.com> LKML-Reference: <49D43CEA.3040609@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-10percpu: generalize embedding first chunk setup helperTejun Heo
Impact: code reorganization Separate out embedding first chunk setup helper from x86 embedding first chunk allocator and put it in mm/percpu.c. This will be used by the default percpu first chunk allocator and possibly by other archs. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-03-10percpu: more flexibility for @dyn_size of pcpu_setup_first_chunk()Tejun Heo
Impact: cleanup, more flexibility for first chunk init Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto. This restriction stemmed from implementation detail and made things a bit less intuitive. This patch allows @dyn_size to be specified regardless of @unit_size and swaps the positions of @dyn_size and @unit_size so that the parameter order makes more sense (static, reserved and dyn sizes followed by enclosing unit_size). While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-03-10percpu: make x86 addr <-> pcpu ptr conversion macros genericTejun Heo
Impact: generic addr <-> pcpu ptr conversion macros There's nothing arch specific about x86 __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr(). With proper __per_cpu_load and __per_cpu_start defined, they'll do the right thing regardless of actual layout. Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c and allow archs to override it as necessary. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-03-07percpu: finer grained locking to break deadlock and allow atomic freeTejun Heo
Impact: fix deadlock and allow atomic free Percpu allocation always uses GFP_KERNEL and whole alloc/free paths were protected by single mutex. All percpu allocations have been from GFP_KERNEL-safe context and the original allocator had this assumption too. However, by protecting both alloc and free paths with the same mutex, the new allocator creates free -> alloc -> GFP_KERNEL dependency which the original allocator didn't have. This can lead to deadlock if free is called from FS or IO paths. Also, in general, allocators are expected to allow free to be called from atomic context. This patch implements finer grained locking to break the deadlock and allow atomic free. For details, please read the "Synchronization rules" comment. While at it, also add CONTEXT: to function comments to describe which context they expect to be called from and what they do to it. This problem was reported by Thomas Gleixner and Peter Zijlstra. http://thread.gmane.org/gmane.linux.kernel/802384 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Peter Zijlstra <peterz@infradead.org>
2009-03-07percpu: move fully free chunk reclamation into a workTejun Heo
Impact: code reorganization for later changes Do fully free chunk reclamation using a work. This change is to prepare for locking changes. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-03-07percpu: move chunk area map extension out of area allocationTejun Heo
Impact: code reorganization for later changes Separate out chunk area map extension into a separate function - pcpu_extend_area_map() - and call it directly from pcpu_alloc() such that pcpu_alloc_area() is guaranteed to have enough area map slots on invocation. With this change, pcpu_alloc_area() does only area allocation and the only failure mode is when the chunk doens't have enough room, so there's no need to distinguish it from memory allocation failures. Make it return -1 on such cases instead of hacky -ENOSPC. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-03-07percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free()Tejun Heo
Impact: code reorganization for later changes With static map handling moved to pcpu_split_block(), pcpu_realloc() only clutters the code and it's also unsuitable for scheduled locking changes. Implement and use pcpu_mem_alloc/free() instead. Signed-off-by: Tejun Heo <tj@kernel.org>
2009-03-06percpu, module: implement reserved allocation and use it for module percpu ↵Tejun Heo
variables Impact: add reserved allocation functionality and use it for module percpu variables This patch implements reserved allocation from the first chunk. When setting up the first chunk, arch can ask to set aside certain number of bytes right after the core static area which is available only through a separate reserved allocator. This will be used primarily for module static percpu variables on architectures with limited relocation range to ensure that the module perpcu symbols are inside the relocatable range. If reserved area is requested, the first chunk becomes reserved and isn't available for regular allocation. If the first chunk also includes piggy-back dynamic allocation area, a separate chunk mapping the same region is created to serve dynamic allocation. The first one is called static first chunk and the second dynamic first chunk. Although they share the page map, their different area map initializations guarantee they serve disjoint areas according to their purposes. If arch doesn't setup reserved area, reserved allocation is handled like any other allocation. Signed-off-by: Tejun Heo <tj@kernel.org>