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2022-12-13Merge branch 'for-6.2' of ↵Linus Torvalds1-4/+3
git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu Pull percpu updates from Dennis Zhou: "Baoquan was nice enough to run some clean ups for percpu" * 'for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu: mm/percpu: remove unused PERCPU_DYNAMIC_EARLY_SLOTS mm/percpu.c: remove the lcm code since block size is fixed at page size mm/percpu: replace the goto with break mm/percpu: add comment to state the empty populated pages accounting mm/percpu: Update the code comment when creating new chunk mm/percpu: use list_first_entry_or_null in pcpu_reclaim_populated() mm/percpu: remove unused pcpu_map_extend_chunks
2022-11-21percpu: adjust the value of PERCPU_DYNAMIC_EARLY_SIZEBaoquan He1-1/+1
LKP reported a build failure as below on the following patch "mm/slub, percpu: correct the calculation of early percpu allocation size" ~~~~~~ In file included from <command-line>: In function 'alloc_kmem_cache_cpus', inlined from 'kmem_cache_open' at mm/slub.c:4340:6: >> >> include/linux/compiler_types.h:357:45: error: call to '__compiletime_assert_474' declared with attribute error: BUILD_BUG_ON failed: PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu) 357 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) ~~~~~~ From the kernel config file provided by LKP, the building was made on arm64 with below Kconfig item enabled: CONFIG_ZONE_DMA=y CONFIG_SLUB_CPU_PARTIAL=y CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_SLUB_STATS=y CONFIG_ARM64_PAGE_SHIFT=16 CONFIG_ARM64_64K_PAGES=y Then we will have: NR_KMALLOC_TYPES:4 KMALLOC_SHIFT_HIGH:17 sizeof(struct kmem_cache_cpu):184 The product of them is 12512, which is bigger than PERCPU_DYNAMIC_EARLY_SIZE, 12K. Hence, the BUILD_BUG_ON in alloc_kmem_cache_cpus() is triggered. Earlier, in commit 099a19d91ca4 ("percpu: allow limited allocation before slab is online"), PERCPU_DYNAMIC_EARLY_SIZE was introduced and set to 12K which is equal to the then PERPCU_DYNAMIC_RESERVE. Later, in commit 1a4d76076cda ("percpu: implement asynchronous chunk population"), PERPCU_DYNAMIC_RESERVE was increased by 8K, while PERCPU_DYNAMIC_EARLY_SIZE was kept unchanged. So, here increase PERCPU_DYNAMIC_EARLY_SIZE by 8K too to accommodate to the slub's requirement. Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Baoquan He <bhe@redhat.com> Acked-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
2022-11-08mm/percpu: remove unused PERCPU_DYNAMIC_EARLY_SLOTSBaoquan He1-4/+3
Since commit 40064aeca35c ("percpu: replace area map allocator with bitmap"), there's no place to use PERCPU_DYNAMIC_EARLY_SLOTS. So clean it up. Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Dennis Zhou <dennis@kernel.org>
2022-01-20mm: percpu: add generic pcpu_populate_pte() functionKefeng Wang1-3/+2
With NEED_PER_CPU_PAGE_FIRST_CHUNK enabled, we need a function to populate pte, this patch adds a generic pcpu populate pte function, pcpu_populate_pte(), which is marked __weak and used on most architectures, but it is overridden on x86, which has its own implementation. Link: https://lkml.kernel.org/r/20211216112359.103822-5-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-20mm: percpu: add generic pcpu_fc_alloc/free funcitonKefeng Wang1-8/+1
With the previous patch, we could add a generic pcpu first chunk allocate and free function to cleanup the duplicated definations on each architecture. Link: https://lkml.kernel.org/r/20211216112359.103822-4-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-20mm: percpu: add pcpu_fc_cpu_to_node_fn_t typedefKefeng Wang1-2/+5
Add pcpu_fc_cpu_to_node_fn_t and pass it into pcpu_fc_alloc_fn_t, pcpu first chunk allocation will call it to alloc memblock on the corresponding node by it, this is prepare for the next patch. Link: https://lkml.kernel.org/r/20211216112359.103822-3-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-18Merge tag 'printk-for-5.16-fixup' of ↵Linus Torvalds1-1/+0
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk fixes from Petr Mladek: - Try to flush backtraces from other CPUs also on the local one. This was a regression caused by printk_safe buffers removal. - Remove header dependency warning. * tag 'printk-for-5.16-fixup' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: Remove printk.h inclusion in percpu.h printk: restore flushing of NMI buffers on remote CPUs after NMI backtraces
2021-11-15printk: Remove printk.h inclusion in percpu.hAndy Shevchenko1-1/+0
After the commit 42a0bb3f7138 ("printk/nmi: generic solution for safe printk in NMI") the printk.h is not needed anymore in percpu.h. Moreover `make headerdep` complains (an excerpt) In file included from linux/printk.h, from linux/dynamic_debug.h:188 from linux/printk.h:559 <-- here from linux/percpu.h:9 from linux/idr.h:17 include/net/9p/client.h:13: warning: recursive header inclusion Yeah, it's not a root cause of this, but removing will help to reduce the noise. Fixes: 42a0bb3f7138 ("printk/nmi: generic solution for safe printk in NMI") Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20211112140749.80042-1-andriy.shevchenko@linux.intel.com
2021-11-06percpu: add __alloc_size attributes for better bounds checkingKees Cook1-3/+3
As already done in GrapheneOS, add the __alloc_size attribute for appropriate percpu allocator interfaces, to provide additional hinting for better bounds checking, assisting CONFIG_FORTIFY_SOURCE and other compiler optimizations. Note that due to the implementation of the percpu API, this is unlikely to ever actually provide compile-time checking beyond very simple non-SMP builds. But, since they are technically allocators, mark them as such. Link: https://lkml.kernel.org/r/20210930222704.2631604-9-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Co-developed-by: Daniel Micay <danielmicay@gmail.com> Signed-off-by: Daniel Micay <danielmicay@gmail.com> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: David Rientjes <rientjes@google.com> Cc: Dwaipayan Ray <dwaipayanray1@gmail.com> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Alexandre Bounine <alex.bou9@gmail.com> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: kernel test robot <lkp@intel.com> Cc: Matt Porter <mporter@kernel.crashing.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-04percpu: Make pcpu_setup_first_chunk() void functionKefeng Wang1-1/+1
pcpu_setup_first_chunk() will panic or BUG_ON if the are some error and doesn't return any error, hence it can be defined to return void. Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Dennis Zhou <dennis@kernel.org> [Dennis: fixed kbuild warning for pcpu_page_first_chunk()]
2019-03-13percpu: set PCPU_BITMAP_BLOCK_SIZE to PAGE_SIZEDennis Zhou1-9/+3
Previously, block size was flexible based on the constraint that the GCD(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) > 1. However, this carried the overhead that keeping a floating number of populated free pages required scanning over the free regions of a chunk. Setting the block size to be fixed at PAGE_SIZE lets us know when an empty page becomes used as we will break a full contig_hint of a block. This means we no longer have to scan the whole chunk upon breaking a contig_hint which empty page management piggybacked off. A later patch takes advantage of this to optimize the allocation path by only scanning forward using the scan_hint introduced later too. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Peng Fan <peng.fan@nxp.com>
2018-08-22/proc/meminfo: add percpu populated pages countDennis Zhou (Facebook)1-0/+2
Currently, percpu memory only exposes allocation and utilization information via debugfs. This more or less is only really useful for understanding the fragmentation and allocation information at a per-chunk level with a few global counters. This is also gated behind a config. BPF and cgroup, for example, have seen an increase in use causing increased use of percpu memory. Let's make it easier for someone to identify how much memory is being used. This patch adds the "Percpu" stat to meminfo to more easily look up how much percpu memory is in use. This number includes the cost for all allocated backing pages and not just insight at the per a unit, per chunk level. Metadata is excluded. I think excluding metadata is fair because the backing memory scales with the numbere of cpus and can quickly outweigh the metadata. It also makes this calculation light. Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-27percpu: update free path to take advantage of contig hintsDennis Zhou (Facebook)1-0/+3
The bitmap allocator must keep metadata consistent. The easiest way is to scan after every allocation for each affected block and the entire chunk. This is rather expensive. The free path can take advantage of current contig hints to prevent scanning within the start and end block. If a scan is needed, it can be done by scanning backwards from the start and forwards from the end to identify the entire free area this can be combined with. The blocks can then be updated by some basic checks rather than complete block scans. A chunk scan happens when the freed area makes a page free, a block free, or spans across blocks. This is necessary as the contig hint at this point could span across blocks. The check uses the minimum of page size and the block size to allow for variable sized blocks. There is a tradeoff here with not updating after every free. It is possible a contig hint in one block can be merged with the contig hint in the next block. This means the contig hint can be off by up to a page. However, if the chunk's contig hint is contained in one block, the contig hint will be accurate. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-27percpu: introduce bitmap metadata blocksDennis Zhou (Facebook)1-0/+12
This patch introduces the bitmap metadata blocks and adds the skeleton of the code that will be used to maintain these blocks. Each chunk's bitmap is made up of full metadata blocks. These blocks maintain basic metadata to help prevent scanning unnecssarily to update hints. Full scanning methods are used for the skeleton and will be replaced in the coming patches. A number of helper functions are added as well to do conversion of pages to blocks and manage offsets. Comments will be updated as the final version of each function is added. There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE, the region size, and unit_size. Every chunk's region (including offsets) is page aligned at the beginning to preserve alignment. The end is aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end can fit with the populated page map which is by page and every metadata block is fully accounted for. The unit_size is already page aligned, but must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata blocks. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-27percpu: replace area map allocator with bitmapDennis Zhou (Facebook)1-1/+0
The percpu memory allocator is experiencing scalability issues when allocating and freeing large numbers of counters as in BPF. Additionally, there is a corner case where iteration is triggered over all chunks if the contig_hint is the right size, but wrong alignment. This patch replaces the area map allocator with a basic bitmap allocator implementation. Each subsequent patch will introduce new features and replace full scanning functions with faster non-scanning options when possible. Implementation: This patchset removes the area map allocator in favor of a bitmap allocator backed by metadata blocks. The primary goal is to provide consistency in performance and memory footprint with a focus on small allocations (< 64 bytes). The bitmap removes the heavy memmove from the freeing critical path and provides a consistent memory footprint. The metadata blocks provide a bound on the amount of scanning required by maintaining a set of hints. In an effort to make freeing fast, the metadata is updated on the free path if the new free area makes a page free, a block free, or spans across blocks. This causes the chunk's contig hint to potentially be smaller than what it could allocate by up to the smaller of a page or a block. If the chunk's contig hint is contained within a block, a check occurs and the hint is kept accurate. Metadata is always kept accurate on allocation, so there will not be a situation where a chunk has a later contig hint than available. Evaluation: I have primarily done testing against a simple workload of allocation of 1 million objects (2^20) of varying size. Deallocation was done by in order, alternating, and in reverse. These numbers were collected after rebasing ontop of a80099a152. I present the worst-case numbers here: Area Map Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 310 | 4770 16B | 557 | 1325 64B | 436 | 273 256B | 776 | 131 1024B | 3280 | 122 Bitmap Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 490 | 70 16B | 515 | 75 64B | 610 | 80 256B | 950 | 100 1024B | 3520 | 200 This data demonstrates the inability for the area map allocator to handle less than ideal situations. In the best case of reverse deallocation, the area map allocator was able to perform within range of the bitmap allocator. In the worst case situation, freeing took nearly 5 seconds for 1 million 4-byte objects. The bitmap allocator dramatically improves the consistency of the free path. The small allocations performed nearly identical regardless of the freeing pattern. While it does add to the allocation latency, the allocation scenario here is optimal for the area map allocator. The area map allocator runs into trouble when it is allocating in chunks where the latter half is full. It is difficult to replicate this, so I present a variant where the pages are second half filled. Freeing was done sequentially. Below are the numbers for this scenario: Area Map Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 4118 | 4892 16B | 1651 | 1163 64B | 598 | 285 256B | 771 | 158 1024B | 3034 | 160 Bitmap Allocator: Object Size | Alloc Time (ms) | Free Time (ms) ---------------------------------------------- 4B | 481 | 67 16B | 506 | 69 64B | 636 | 75 256B | 892 | 90 1024B | 3262 | 147 The data shows a parabolic curve of performance for the area map allocator. This is due to the memmove operation being the dominant cost with the lower object sizes as more objects are packed in a chunk and at higher object sizes, the traversal of the chunk slots is the dominating cost. The bitmap allocator suffers this problem as well. The above data shows the inability to scale for the allocation path with the area map allocator and that the bitmap allocator demonstrates consistent performance in general. The second problem of additional scanning can result in the area map allocator completing in 52 minutes when trying to allocate 1 million 4-byte objects with 8-byte alignment. The same workload takes approximately 16 seconds to complete for the bitmap allocator. V2: Fixed a bug in pcpu_alloc_first_chunk end_offset was setting the bitmap using bytes instead of bits. Added a comment to pcpu_cnt_pop_pages to explain bitmap_weight. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-07-26percpu: increase minimum percpu allocation size and align first regionsDennis Zhou (Facebook)1-0/+4
This patch increases the minimum allocation size of percpu memory to 4-bytes. This change will help minimize the metadata overhead associated with the bitmap allocator. The assumption is that most allocations will be of objects or structs greater than 2 bytes with integers or longs being used rather than shorts. The first chunk regions are now aligned with the minimum allocation size. The reserved region is expected to be set as a multiple of the minimum allocation size. The static region is aligned up and the delta is removed from the dynamic size. This works because the dynamic size is increased to be page aligned. If the static size is not minimum allocation size aligned, then there must be a gap that is added to the dynamic size. The dynamic size will never be smaller than the set value. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-03-16locking/lockdep: Handle statically initialized PER_CPU locks properlyThomas Gleixner1-0/+1
If a PER_CPU struct which contains a spin_lock is statically initialized via: DEFINE_PER_CPU(struct foo, bla) = { .lock = __SPIN_LOCK_UNLOCKED(bla.lock) }; then lockdep assigns a seperate key to each lock because the logic for assigning a key to statically initialized locks is to use the address as the key. With per CPU locks the address is obvioulsy different on each CPU. That's wrong, because all locks should have the same key. To solve this the following modifications are required: 1) Extend the is_kernel/module_percpu_addr() functions to hand back the canonical address of the per CPU address, i.e. the per CPU address minus the per CPU offset. 2) Check the lock address with these functions and if the per CPU check matches use the returned canonical address as the lock key, so all per CPU locks have the same key. 3) Move the static_obj(key) check into look_up_lock_class() so this check can be avoided for statically initialized per CPU locks. That's required because the canonical address fails the static_obj(key) check for obvious reasons. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ Merged Dan's fixups for !MODULES and !SMP into this patch. ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Murphy <dmurphy@ti.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20170227143736.pectaimkjkan5kow@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-21printk/nmi: generic solution for safe printk in NMIPetr Mladek1-3/+0
printk() takes some locks and could not be used a safe way in NMI context. The chance of a deadlock is real especially when printing stacks from all CPUs. This particular problem has been addressed on x86 by the commit a9edc8809328 ("x86/nmi: Perform a safe NMI stack trace on all CPUs"). The patchset brings two big advantages. First, it makes the NMI backtraces safe on all architectures for free. Second, it makes all NMI messages almost safe on all architectures (the temporary buffer is limited. We still should keep the number of messages in NMI context at minimum). Note that there already are several messages printed in NMI context: WARN_ON(in_nmi()), BUG_ON(in_nmi()), anything being printed out from MCE handlers. These are not easy to avoid. This patch reuses most of the code and makes it generic. It is useful for all messages and architectures that support NMI. The alternative printk_func is set when entering and is reseted when leaving NMI context. It queues IRQ work to copy the messages into the main ring buffer in a safe context. __printk_nmi_flush() copies all available messages and reset the buffer. Then we could use a simple cmpxchg operations to get synchronized with writers. There is also used a spinlock to get synchronized with other flushers. We do not longer use seq_buf because it depends on external lock. It would be hard to make all supported operations safe for a lockless use. It would be confusing and error prone to make only some operations safe. The code is put into separate printk/nmi.c as suggested by Steven Rostedt. It needs a per-CPU buffer and is compiled only on architectures that call nmi_enter(). This is achieved by the new HAVE_NMI Kconfig flag. The are MN10300 and Xtensa architectures. We need to clean up NMI handling there first. Let's do it separately. The patch is heavily based on the draft from Peter Zijlstra, see https://lkml.org/lkml/2015/6/10/327 [arnd@arndb.de: printk-nmi: use %zu format string for size_t] [akpm@linux-foundation.org: min_t->min - all types are size_t here] Signed-off-by: Petr Mladek <pmladek@suse.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Suggested-by: Steven Rostedt <rostedt@goodmis.org> Cc: Jan Kara <jack@suse.cz> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> [arm part] Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jiri Kosina <jkosina@suse.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: David Miller <davem@davemloft.net> Cc: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-16percpu: remove PERCPU_ENOUGH_ROOM which is stale definitionJungseok Lee1-6/+0
As pure cleanup, this patch removes PERCPU_ENOUGH_ROOM which is not used any more. That is, no code refers to the definition. Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-11-21printk/percpu: Define printk_func when printk is not definedSteven Rostedt (Red Hat)1-0/+1
To avoid include hell, the per_cpu variable printk_func was declared in percpu.h. But it is only defined if printk is defined. As users of printk may also use the printk_func variable, it needs to be defined even if CONFIG_PRINTK is not. Also add a printk.h include in percpu.h just to be safe. Link: http://lkml.kernel.org/r/20141121183215.01ba539c@canb.auug.org.au Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-11-20printk: Add per_cpu printk func to allow printk to be divertedSteven Rostedt (Red Hat)1-0/+3
Being able to divert printk to call another function besides the normal logging is useful for such things like NMI handling. If some functions are to be called from NMI that does printk() it is possible to lock up the box if the nmi handler triggers when another printk is happening. One example of this use is to perform a stack trace on all CPUs via NMI. But if the NMI is to do the printk() it can cause the system to lock up. By allowing the printk to be diverted to another function that can safely record the printk output and then print it when it in a safe context then NMIs will be safe to call these functions like show_regs(). Link: http://lkml.kernel.org/p/20140619213952.209176403@goodmis.org Tested-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Petr Mladek <pmladek@suse.cz> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-02percpu: implement asynchronous chunk populationTejun Heo1-2/+2
The percpu allocator now supports atomic allocations by only allocating from already populated areas but the mechanism to ensure that there's adequate amount of populated areas was missing. This patch expands pcpu_balance_work so that in addition to freeing excess free chunks it also populates chunks to maintain an adequate level of populated areas. pcpu_alloc() schedules pcpu_balance_work if the amount of free populated areas is too low or after an atomic allocation failure. * PERPCU_DYNAMIC_RESERVE is increased by two pages to account for PCPU_EMPTY_POP_PAGES_LOW. * pcpu_async_enabled is added to gate both async jobs - chunk->map_extend_work and pcpu_balance_work - so that we don't end up scheduling them while the needed subsystems aren't up yet. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-02percpu: implement [__]alloc_percpu_gfp()Tejun Heo1-2/+7
Now that pcpu_alloc_area() can allocate only from populated areas, it's easy to add atomic allocation support to [__]alloc_percpu(). Update pcpu_alloc() so that it accepts @gfp and skips all the blocking operations and allocates only from the populated areas if @gfp doesn't contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp() are added. While this means that atomic allocations are possible, this isn't complete yet as there's no mechanism to ensure that certain amount of populated areas is kept available and atomic allocations may keep failing under certain conditions. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-06-18percpu: move {raw|this}_cpu_*() definitions to include/linux/percpu-defs.hTejun Heo1-208/+0
We're in the process of moving all percpu accessors and operations to include/linux/percpu-defs.h so that they're available to arch headers without having to include full include/linux/percpu.h which may cause cyclic inclusion dependency. This patch moves {raw|this}_cpu_*() definitions from include/linux/percpu.h to include/linux/percpu-defs.h. The code is moved mostly verbatim; however, raw_cpu_*() are placed above this_cpu_*() which is more conventional as the raw operations may be used to defined other variants. This is pure reorganization. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Christoph Lameter <cl@linux.com>
2014-06-18percpu: move generic {raw|this}_cpu_*_N() definitions to ↵Tejun Heo1-344/+0
include/asm-generic/percpu.h {raw|this}_cpu_*_N() operations are expected to be provided by archs and the generic definitions are provided as fallbacks. As such, these firmly belong to include/asm-generic/percpu.h. Move the generic definitions to include/asm-generic/percpu.h. The code is moved mostly verbatim; however, raw_cpu_*_N() are placed above this_cpu_*_N() which is more conventional as the raw operations may be used to defined other variants. This is pure reorganization. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Christoph Lameter <cl@linux.com>
2014-06-18percpu: only allow sized arch overrides for {raw|this}_cpu_*() opsTejun Heo1-89/+5
Currently, percpu allows two separate methods for overriding {raw|this}_cpu_*() ops - for a given operation, an arch can provide whole replacement or sized sub operations to override specific parts of it. e.g. arch either can provide this_cpu_add() or this_cpu_add_4() to override only the 4 byte operation. While quite flexible on a glance, the dual-overriding scheme complicates the code path for no actual gain. It compilcates the already complex operation definitions and if an arch wants to override all sizes, it can easily provide all variants anyway. In fact, no arch is actually making use of whole operation override. Another oddity is that __this_cpu_*() operations are defined in the same way as raw_cpu_*() but ignores full overrides of the raw_cpu_*() and doesn't allow full operation override, so if an arch provides whole overrides for raw_cpu_*() operations __this_cpu_*() ends up using the generic implementations. More importantly, it takes away the layering between arch-specific and generic parts making it impossible for the generic part to implement arch-independent features on top of arch-specific overrides. This patch removes the support for whole operation overrides. As no arch is using it, this doesn't cause any actual difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Christoph Lameter <cl@linux.com>
2014-06-18percpu: move accessors from include/linux/percpu.h to percpu-defs.hTejun Heo1-37/+0
include/linux/percpu-defs.h is gonna host all accessors and operations so that arch headers can make use of them too without worrying about circular dependency through include/linux/percpu.h. This patch moves the following accessors from include/linux/percpu.h to include/linux/percpu-defs.h. * get/put_cpu_var() * get/put_cpu_ptr() * per_cpu_ptr() This is pure reorgniazation. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Christoph Lameter <cl@linux.com>
2014-06-10Merge branch 'for-3.16' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu Pull percpu updates from Tejun Heo: "Nothing too exciting. percpu_ref is going through some interface changes and getting new features with more changes in the pipeline but given its young age and few users, it's very low impact" * 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu-refcount: implement percpu_ref_tryget() percpu-refcount: rename percpu_ref_tryget() to percpu_ref_tryget_live() percpu: Replace __get_cpu_var with this_cpu_ptr
2014-05-14percpu: Fix raw_cpu_inc_return()Paul E. McKenney1-1/+1
The definition for raw_cpu_add_return() uses the operation prefix "raw_add_return_", but the definitions in the various percpu.h files expect "raw_cpu_add_return_". This commit therefore appropriately adjusts the definition of raw_cpu_add_return(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Christoph Lameter <cl@linux.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-04-15percpu: Replace __get_cpu_var with this_cpu_ptrChristoph Lameter1-1/+1
__this_cpu_ptr is being phased out. Use raw_cpu_ptr instead which was introduced in 3.15-rc1. One case of using __get_cpu_var in the get_cpu_var macro for address calculation was remaining in include/linux/percpu.h. tj: Updated patch description. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-04-08percpu: add preemption checks to __this_cpu opsChristoph Lameter1-10/+29
We define a check function in order to avoid trouble with the include files. Then the higher level __this_cpu macros are modified to invoke the preemption check. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Christoph Lameter <cl@linux.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Tejun Heo <tj@kernel.org> Tested-by: Grygorii Strashko <grygorii.strashko@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-08percpu: add raw_cpu_opsChristoph Lameter1-136/+195
The kernel has never been audited to ensure that this_cpu operations are consistently used throughout the kernel. The code generated in many places can be improved through the use of this_cpu operations (which uses a segment register for relocation of per cpu offsets instead of performing address calculations). The patch set also addresses various consistency issues in general with the per cpu macros. A. The semantics of __this_cpu_ptr() differs from this_cpu_ptr only because checks are skipped. This is typically shown through a raw_ prefix. So this patch set changes the places where __this_cpu_ptr() is used to raw_cpu_ptr(). B. There has been the long term wish by some that __this_cpu operations would check for preemption. However, there are cases where preemption checks need to be skipped. This patch set adds raw_cpu operations that do not check for preemption and then adds preemption checks to the __this_cpu operations. C. The use of __get_cpu_var is always a reference to a percpu variable that can also be handled via a this_cpu operation. This patch set replaces all uses of __get_cpu_var with this_cpu operations. D. We can then use this_cpu RMW operations in various places replacing sequences of instructions by a single one. E. The use of this_cpu operations throughout will allow other arches than x86 to implement optimized references and RMV operations to work with per cpu local data. F. The use of this_cpu operations opens up the possibility to further optimize code that relies on synchronization through per cpu data. The patch set works in a couple of stages: I. Patch 1 adds the additional raw_cpu operations and raw_cpu_ptr(). Also converts the existing __this_cpu_xx_# primitive in the x86 code to raw_cpu_xx_#. II. Patch 2-4 use the raw_cpu operations in places that would give us false positives once they are enabled. III. Patch 5 adds preemption checks to __this_cpu operations to allow checking if preemption is properly disabled when these functions are used. IV. Patches 6-20 are patches that simply replace uses of __get_cpu_var with this_cpu_ptr. They do not depend on any changes to the percpu code. No preemption tests are skipped if they are applied. V. Patches 21-46 are conversion patches that use this_cpu operations in various kernel subsystems/drivers or arch code. VI. Patches 47/48 (not included in this series) remove no longer used functions (__this_cpu_ptr and __get_cpu_var). These should only be applied after all the conversion patches have made it and after we have done additional passes through the kernel to ensure that none of the uses of these functions remain. This patch (of 46): The patches following this one will add preemption checks to __this_cpu ops so we need to have an alternative way to use this_cpu operations without preemption checks. raw_cpu_ops will be the basis for all other ops since these will be the operations that do not implement any checks. Primitive operations are renamed by this patch from __this_cpu_xxx to raw_cpu_xxxx. Also change the uses of the x86 percpu primitives in preempt.h. These depend directly on asm/percpu.h (header #include nesting issue). Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Christoph Lameter <cl@linux.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Alex Shi <alex.shi@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Bryan Wu <cooloney@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: David Daney <david.daney@cavium.com> Cc: David Miller <davem@davemloft.net> Cc: David S. Miller <davem@davemloft.net> Cc: Dimitri Sivanich <sivanich@sgi.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Hedi Berriche <hedi@sgi.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James Hogan <james.hogan@imgtec.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: John Stultz <john.stultz@linaro.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Mike Travis <travis@sgi.com> Cc: Neil Brown <neilb@suse.de> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Robert Richter <rric@kernel.org> Cc: Russell King <linux@arm.linux.org.uk> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Wim Van Sebroeck <wim@iguana.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-24mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGESasha Levin1-0/+1
Most of the VM_BUG_ON assertions are performed on a page. Usually, when one of these assertions fails we'll get a BUG_ON with a call stack and the registers. I've recently noticed based on the requests to add a small piece of code that dumps the page to various VM_BUG_ON sites that the page dump is quite useful to people debugging issues in mm. This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what VM_BUG_ON() does, also dumps the page before executing the actual BUG_ON. [akpm@linux-foundation.org: fix up includes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13Merge branch 'for-3.13' of ↵Linus Torvalds1-32/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu Pull percpu changes from Tejun Heo: "Two smallish changes for percpu. Two patches to remove unused this_cpu_xor() and one to fix a bug in percpu init failure path so that it can reach the proper BUG() instead of oopsing earlier" * 'for-3.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: x86: remove this_cpu_xor() implementation percpu: remove this_cpu_xor() implementation percpu: fix bootmem error handling in pcpu_page_first_chunk()
2013-10-31percpu: fix this_cpu_sub() subtrahend casting for unsignedsGreg Thelen1-4/+4
this_cpu_sub() is implemented as negation and addition. This patch casts the adjustment to the counter type before negation to sign extend the adjustment. This helps in cases where the counter type is wider than an unsigned adjustment. An alternative to this patch is to declare such operations unsupported, but it seemed useful to avoid surprises. This patch specifically helps the following example: unsigned int delta = 1 preempt_disable() this_cpu_write(long_counter, 0) this_cpu_sub(long_counter, delta) preempt_enable() Before this change long_counter on a 64 bit machine ends with value 0xffffffff, rather than 0xffffffffffffffff. This is because this_cpu_sub(pcp, delta) boils down to this_cpu_add(pcp, -delta), which is basically: long_counter = 0 + 0xffffffff Also apply the same cast to: __this_cpu_sub() __this_cpu_sub_return() this_cpu_sub_return() All percpu_test.ko passes, especially the following cases which previously failed: l -= ui_one; __this_cpu_sub(long_counter, ui_one); CHECK(l, long_counter, -1); l -= ui_one; this_cpu_sub(long_counter, ui_one); CHECK(l, long_counter, -1); CHECK(l, long_counter, 0xffffffffffffffff); ul -= ui_one; __this_cpu_sub(ulong_counter, ui_one); CHECK(ul, ulong_counter, -1); CHECK(ul, ulong_counter, 0xffffffffffffffff); ul = this_cpu_sub_return(ulong_counter, ui_one); CHECK(ul, ulong_counter, 2); ul = __this_cpu_sub_return(ulong_counter, ui_one); CHECK(ul, ulong_counter, 1); Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-27percpu: remove this_cpu_xor() implementationHeiko Carstens1-32/+0
There is not a single user in the whole kernel. Besides that this_cpu_xor() is broken anyway since it gets translated to this_cpu_or() (see __pcpu_size_call() line). So instead of fixing an unused definition just remove it. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-10-05sections: fix section conflicts in mm/percpu.cAndi Kleen1-1/+1
Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-15percpu: remove percpu_xxx() functionsAlex Shi1-54/+0
Remove percpu_xxx serial functions, all of them were replaced by this_cpu_xxx or __this_cpu_xxx serial functions Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Christoph Lameter <cl@gentwo.org> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-03-04percpu: fix __this_cpu_{sub,inc,dec}_return() definitionKonstantin Khlebnikov1-3/+3
This patch adds missed "__" prefixes, otherwise these functions works as irq/preemption safe. Reported-by: Torsten Kaiser <just.for.lkml@googlemail.com> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-02-21percpu: use raw_local_irq_* in _this_cpu opMing Lei1-10/+10
It doesn't make sense to trace irq off or do irq flags lock proving inside 'this_cpu' operations, so replace local_irq_* with raw_local_irq_* in 'this_cpu' op. Also the patch fixes onelockdep warning[1] by the replacement, see below: In commit: 933393f58fef9963eac61db8093689544e29a600(percpu: Remove irqsafe_cpu_xxx variants), local_irq_save/restore(flags) are added inside this_cpu_inc operation, so that trace_hardirqs_off_caller will be called by trace_hardirqs_on_caller directly because __debug_atomic_inc is implemented as this_cpu_inc, which may trigger the lockdep warning[1], for example in the below ARM scenary: kernel_thread_helper /*irq disabled*/ ->trace_hardirqs_on_caller /*hardirqs_enabled was set*/ ->trace_hardirqs_off_caller /*hardirqs_enabled cleared*/ __this_cpu_add(redundant_hardirqs_on) ->trace_hardirqs_off_caller /*irq disabled, so call here*/ The 'unannotated irqs-on' warning will be triggered somewhere because irq is just enabled after the irq trace in kernel_thread_helper. [1], [ 0.162841] ------------[ cut here ]------------ [ 0.167694] WARNING: at kernel/lockdep.c:3493 check_flags+0xc0/0x1d0() [ 0.174468] Modules linked in: [ 0.177703] Backtrace: [ 0.180328] [<c00171f0>] (dump_backtrace+0x0/0x110) from [<c0412320>] (dump_stack+0x18/0x1c) [ 0.189086] r6:c051f778 r5:00000da5 r4:00000000 r3:60000093 [ 0.195007] [<c0412308>] (dump_stack+0x0/0x1c) from [<c00410e8>] (warn_slowpath_common+0x54/0x6c) [ 0.204223] [<c0041094>] (warn_slowpath_common+0x0/0x6c) from [<c0041124>] (warn_slowpath_null+0x24/0x2c) [ 0.214111] r8:00000000 r7:00000000 r6:ee069598 r5:60000013 r4:ee082000 [ 0.220825] r3:00000009 [ 0.223693] [<c0041100>] (warn_slowpath_null+0x0/0x2c) from [<c0088f38>] (check_flags+0xc0/0x1d0) [ 0.232910] [<c0088e78>] (check_flags+0x0/0x1d0) from [<c008d348>] (lock_acquire+0x4c/0x11c) [ 0.241668] [<c008d2fc>] (lock_acquire+0x0/0x11c) from [<c0415aa4>] (_raw_spin_lock+0x3c/0x74) [ 0.250610] [<c0415a68>] (_raw_spin_lock+0x0/0x74) from [<c010a844>] (set_task_comm+0x20/0xc0) [ 0.259521] r6:ee069588 r5:ee0691c0 r4:ee082000 [ 0.264404] [<c010a824>] (set_task_comm+0x0/0xc0) from [<c0060780>] (kthreadd+0x28/0x108) [ 0.272857] r8:00000000 r7:00000013 r6:c0044a08 r5:ee0691c0 r4:ee082000 [ 0.279571] r3:ee083fe0 [ 0.282470] [<c0060758>] (kthreadd+0x0/0x108) from [<c0044a08>] (do_exit+0x0/0x6dc) [ 0.290405] r5:c0060758 r4:00000000 [ 0.294189] ---[ end trace 1b75b31a2719ed1c ]--- [ 0.299041] possible reason: unannotated irqs-on. [ 0.303955] irq event stamp: 5 [ 0.307159] hardirqs last enabled at (4): [<c001331c>] no_work_pending+0x8/0x2c [ 0.314880] hardirqs last disabled at (5): [<c0089b08>] trace_hardirqs_on_caller+0x60/0x26c [ 0.323547] softirqs last enabled at (0): [<c003f754>] copy_process+0x33c/0xef4 [ 0.331207] softirqs last disabled at (0): [< (null)>] (null) [ 0.337585] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000 Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-02-21percpu: fix generic definition of __this_cpu_add_and_return()Konstantin Khlebnikov1-1/+2
This patch adds missed "__" into function prefix. Otherwise on all archectures (except x86) it expands to irq/preemtion-safe variant: _this_cpu_generic_add_return(), which do extra irq-save/irq-restore. Optimal generic implementation is __this_cpu_generic_add_return(). Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2011-12-22percpu: Remove irqsafe_cpu_xxx variantsChristoph Lameter1-168/+22
We simply say that regular this_cpu use must be safe regardless of preemption and interrupt state. That has no material change for x86 and s390 implementations of this_cpu operations. However, arches that do not provide their own implementation for this_cpu operations will now get code generated that disables interrupts instead of preemption. -tj: This is part of on-going percpu API cleanup. For detailed discussion of the subject, please refer to the following thread. http://thread.gmane.org/gmane.linux.kernel/1222078 Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org> LKML-Reference: <alpine.DEB.2.00.1112221154380.11787@router.home>
2011-06-03slub: always align cpu_slab to honor cmpxchg_double requirementChris Metcalf1-0/+3
On an architecture without CMPXCHG_LOCAL but with DEBUG_VM enabled, the VM_BUG_ON() in __pcpu_double_call_return_bool() will cause an early panic during boot unless we always align cpu_slab properly. In principle we could remove the alignment-testing VM_BUG_ON() for architectures that don't have CMPXCHG_LOCAL, but leaving it in means that new code will tend not to break x86 even if it is introduced on another platform, and it's low cost to require alignment. Acked-by: David Rientjes <rientjes@google.com> Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
2011-05-05slub: Fix the lockless code on 32-bit platforms with no 64-bit cmpxchgThomas Gleixner1-1/+1
The SLUB allocator use of the cmpxchg_double logic was wrong: it actually needs the irq-safe one. That happens automatically when we use the native unlocked 'cmpxchg8b' instruction, but when compiling the kernel for older x86 CPUs that do not support that instruction, we fall back to the generic emulation code. And if you don't specify that you want the irq-safe version, the generic code ends up just open-coding the cmpxchg8b equivalent without any protection against interrupts or preemption. Which definitely doesn't work for SLUB. This was reported by Werner Landgraf <w.landgraf@ru.ru>, who saw instability with his distro-kernel that was compiled to support pretty much everything under the sun. Most big Linux distributions tend to compile for PPro and later, and would never have noticed this problem. This also fixes the prototypes for the irqsafe cmpxchg_double functions to use 'bool' like they should. [ Btw, that whole "generic code defaults to no protection" design just sounds stupid - if the code needs no protection, there is no reason to use "cmpxchg_double" to begin with. So we should probably just remove the unprotected version entirely as pointless. - Linus ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reported-and-tested-by: werner <w.landgraf@ru.ru> Acked-and-tested-by: Ingo Molnar <mingo@elte.hu> Acked-by: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1105041539050.3005@ionos Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-28percpu: Generic support for this_cpu_cmpxchg_double()Christoph Lameter1-0/+128
Introduce this_cpu_cmpxchg_double(). this_cpu_cmpxchg_double() allows the comparison between two consecutive words and replaces them if there is a match. bool this_cpu_cmpxchg_double(pcp1, pcp2, old_word1, old_word2, new_word1, new_word2) this_cpu_cmpxchg_double does not return the old value (difficult since there are two words) but a boolean indicating if the operation was successful. The first percpu variable must be double word aligned! -tj: Updated to return bool instead of int, converted size check to BUILD_BUG_ON() instead of VM_BUG_ON() and other cosmetic changes. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2010-12-18percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg supportChristoph Lameter1-1/+133
Generic code to provide new per cpu atomic features this_cpu_cmpxchg this_cpu_xchg Fallback occurs to functions using interrupts disable/enable to ensure correct per cpu atomicity. Fallback to regular cmpxchg and xchg is not possible since per cpu atomic semantics include the guarantee that the current cpus per cpu data is accessed atomically. Use of regular cmpxchg and xchg requires the determination of the address of the per cpu data before regular cmpxchg or xchg which therefore cannot be atomically included in an xchg or cmpxchg without segment override. tj: - Relocated new ops to conform better to the general organization. - This patch contains a trivial comment fix. Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2010-12-17percpu,x86: relocate this_cpu_add_return() and friendsTejun Heo1-30/+30
- include/linux/percpu.h: this_cpu_add_return() and friends were located next to __this_cpu_add_return(). However, the overall organization is to first group by preemption safeness. Relocate this_cpu_add_return() and friends to preemption-safe area. - arch/x86/include/asm/percpu.h: Relocate percpu_add_return_op() after other more basic operations. Relocate [__]this_cpu_add_return_8() so that they're first grouped by preemption safeness. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com>
2010-12-17percpu: Generic support for this_cpu_add, sub, dec, inc_returnChristoph Lameter1-0/+71
Introduce generic support for this_cpu_add_return etc. The fallback is to realize these operations with simpler __this_cpu_ops. tj: - Reformatted __cpu_size_call_return2() to make it more consistent with its neighbors. - Dropped unnecessary temp variable ret__ from __this_cpu_generic_add_return(). Reviewed-by: Tejun Heo <tj@kernel.org> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2010-10-23Merge branch 'for-linus' of ↵Linus Torvalds1-25/+6
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: update comments to reflect that percpu allocations are always zero-filled percpu: Optimize __get_cpu_var() x86, percpu: Optimize this_cpu_ptr percpu: clear memory allocated with the km allocator percpu: fix build breakage on s390 and cleanup build configuration tests percpu: use percpu allocator on UP too percpu: reduce PCPU_MIN_UNIT_SIZE to 32k vmalloc: pcpu_get/free_vm_areas() aren't needed on UP Fixed up trivial conflicts in include/linux/percpu.h