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* License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman2017-11-021-0/+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>
* locking/mutex: Initialize mutex_waiter::ww_ctx with poison when debuggingNicolai Hähnle2017-01-141-0/+1
| | | | | | | | | | | | | | | | | | | Help catch cases where mutex_lock is used directly on w/w mutexes, which otherwise result in the w/w tasks reading uninitialized data. Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Maarten Lankhorst <dev@mblankhorst.nl> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dri-devel@lists.freedesktop.org Link: http://lkml.kernel.org/r/1482346000-9927-12-git-send-email-nhaehnle@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* mm/page_poisoning.c: allow for zero poisoningLaura Abbott2016-03-151-0/+4
| | | | | | | | | | | | | | | | | | | | | | | By default, page poisoning uses a poison value (0xaa) on free. If this is changed to 0, the page is not only sanitized but zeroing on alloc with __GFP_ZERO can be skipped as well. The tradeoff is that detecting corruption from the poisoning is harder to detect. This feature also cannot be used with hibernation since pages are not guaranteed to be zeroed after hibernation. Credit to Grsecurity/PaX team for inspiring this work Signed-off-by: Laura Abbott <labbott@fedoraproject.org> Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mathias Krause <minipli@googlemail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jianyu Zhan <nasa4836@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* include/linux/poison.h: use POISON_POINTER_DELTA for poison pointersVasily Kulikov2016-01-161-2/+2
| | | | | | | | | | | | | | TIMER_ENTRY_STATIC and TAIL_MAPPING are defined as poison pointers which should point to nowhere. Redefine them using POISON_POINTER_DELTA arithmetics to make sure they really point to non-mappable area declared by the target architecture. Signed-off-by: Vasily Kulikov <segoon@openwall.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Solar Designer <solar@openwall.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: sanitize page->mapping for tail pagesKirill A. Shutemov2016-01-151-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We don't define meaning of page->mapping for tail pages. Currently it's always NULL, which can be inconsistent with head page and potentially lead to problems. Let's poison the pointer to catch all illigal uses. page_rmapping(), page_mapping() and page_anon_vma() are changed to look on head page. The only illegal use I've caught so far is __GPF_COMP pages from sound subsystem, mapped with PTEs. do_shared_fault() is changed to use page_rmapping() instead of direct access to fault_page->mapping. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* include/linux/poison.h: remove not-used poison pointer macrosVasily Kulikov2015-09-101-7/+0
| | | | | | | | | Signed-off-by: Vasily Kulikov <segoon@openwall.com> Cc: Solar Designer <solar@openwall.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* include/linux/poison.h: fix LIST_POISON{1,2} offsetVasily Kulikov2015-09-101-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | Poison pointer values should be small enough to find a room in non-mmap'able/hardly-mmap'able space. E.g. on x86 "poison pointer space" is located starting from 0x0. Given unprivileged users cannot mmap anything below mmap_min_addr, it should be safe to use poison pointers lower than mmap_min_addr. The current poison pointer values of LIST_POISON{1,2} might be too big for mmap_min_addr values equal or less than 1 MB (common case, e.g. Ubuntu uses only 0x10000). There is little point to use such a big value given the "poison pointer space" below 1 MB is not yet exhausted. Changing it to a smaller value solves the problem for small mmap_min_addr setups. The values are suggested by Solar Designer: http://www.openwall.com/lists/oss-security/2015/05/02/6 Signed-off-by: Vasily Kulikov <segoon@openwall.com> Cc: Solar Designer <solar@openwall.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memblock: Kill sentinel entries at the end of static region arraysTejun Heo2011-12-081-6/+0
| | | | | | | | | | memblock no longer depends on having one more entry at the end during addition making the sentinel entries at the end of region arrays not too useful. Remove the sentinels. This eases further updates. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Yinghai Lu <yinghai@kernel.org>
* mm/memblock.c: avoid abuse of RED_INACTIVEAndrew Morton2011-07-251-0/+6
| | | | | | | | | | | | | | | | RED_INACTIVE is a slab thing, and reusing it for memblock was inappropriate, because memblock is dealing with phys_addr_t's which have a Kconfigurable sizeof(). Create a new poison type for this application. Fixes the sparse warning warning: cast truncates bits from constant value (9f911029d74e35b becomes 9d74e35b) Reported-by: H Hartley Sweeten <hartleys@visionengravers.com> Tested-by: H Hartley Sweeten <hartleys@visionengravers.com> Acked-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hugetlb, rmap: add reverse mapping for hugepageNaoya Horiguchi2010-08-111-9/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds reverse mapping feature for hugepage by introducing mapcount for shared/private-mapped hugepage and anon_vma for private-mapped hugepage. While hugepage is not currently swappable, reverse mapping can be useful for memory error handler. Without this patch, memory error handler cannot identify processes using the bad hugepage nor unmap it from them. That is: - for shared hugepage: we can collect processes using a hugepage through pagecache, but can not unmap the hugepage because of the lack of mapcount. - for privately mapped hugepage: we can neither collect processes nor unmap the hugepage. This patch solves these problems. This patch include the bug fix given by commit 23be7468e8, so reverts it. Dependency: "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h" ChangeLog since May 24. - create hugetlb_inline.h and move is_vm_hugetlb_index() in it. - move functions setting up anon_vma for hugepage into mm/rmap.c. ChangeLog since May 13. - rebased to 2.6.34 - fix logic error (in case that private mapping and shared mapping coexist) - move is_vm_hugetlb_page() into include/linux/mm.h to use this function from linear_page_index() - define and use linear_hugepage_index() instead of compound_order() - use page_move_anon_rmap() in hugetlb_cow() - copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart. - revert commit 24be7468 completely Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Acked-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andi Kleen <ak@linux.intel.com>
* hugetlb: fix infinite loop in get_futex_key() when backed by huge pagesMel Gorman2010-04-241-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | If a futex key happens to be located within a huge page mapped MAP_PRIVATE, get_futex_key() can go into an infinite loop waiting for a page->mapping that will never exist. See https://bugzilla.redhat.com/show_bug.cgi?id=552257 for more details about the problem. This patch makes page->mapping a poisoned value that includes PAGE_MAPPING_ANON mapped MAP_PRIVATE. This is enough for futex to continue but because of PAGE_MAPPING_ANON, the poisoned value is not dereferenced or used by futex. No other part of the VM should be dereferencing the page->mapping of a hugetlbfs page as its page cache is not on the LRU. This patch fixes the problem with the test case described in the bugzilla. [akpm@linux-foundation.org: mel cant spel] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Darren Hart <darren@dvhart.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* core, x86: make LIST_POISON less deadlyAvi Kivity2010-01-111-2/+14
| | | | | | | | | | | | | | | | | | | | | | | | The list macros use LIST_POISON1 and LIST_POISON2 as undereferencable pointers in order to trap erronous use of freed list_heads. Unfortunately userspace can arrange for those pointers to actually be dereferencable, potentially turning an oops to an expolit. To avoid this allow architectures (currently x86_64 only) to override the default values for these pointers with truly-undereferencable values. This is easy on x86_64 as the virtual address space is large and contains areas that cannot be mapped. Other 64-bit architectures will likely find similar unmapped ranges. [ingo: switch to 0xdead000000000000 as the unmapped area] [ingo: add comments, cleanup] [jaswinder: eliminate sparse warnings] Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* flex_array: poison free elementsDavid Rientjes2009-09-221-0/+3
| | | | | | | | | | | | | | | | | | | | | | Newly initialized flex_array's and/or flex_array_part's are now poisoned with a new poison value, FLEX_ARRAY_FREE. It's value is similar to POISON_FREE used in the various slab allocators, but is different to distinguish between flex array's poisoned kmem and slab allocator poisoned kmem. This will allow us to identify flex_array_part's that only contain free elements (and free them with an addition to the flex_array API). This could also be extended in the future to identify `get' uses on elements that have not been `put'. If __GFP_ZERO is passed for a part's gfp mask, the poisoning is avoided. These elements are considered to be in-use since they have been initialized. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* generic debug pageallocAkinobu Mita2009-04-011-0/+3
| | | | | | | | | | | | | | | | CONFIG_DEBUG_PAGEALLOC is now supported by x86, powerpc, sparc64, and s390. This patch implements it for the rest of the architectures by filling the pages with poison byte patterns after free_pages() and verifying the poison patterns before alloc_pages(). This generic one cannot detect invalid page accesses immediately but invalid read access may cause invalid dereference by poisoned memory and invalid write access can be detected after a long delay. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* debugobjects: add timer specific object debugging codeThomas Gleixner2008-04-301-0/+7
| | | | | | | | | | | | | | Add calls to the generic object debugging infrastructure and provide fixup functions which allow to keep the system alive when recoverable problems have been detected by the object debugging core code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Greg KH <greg@kroah.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* jbd2: JBD_XXX to JBD2_XXX naming cleanupMingming Cao2007-10-171-1/+2
| | | | | | | change JBD_XXX macros to JBD2_XXX in JBD2/Ext4 Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
* Increase slab redzone to 64bitsDavid Woodhouse2007-05-081-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are two problems with the existing redzone implementation. Firstly, it's causing misalignment of structures which contain a 64-bit integer, such as netfilter's 'struct ipt_entry' -- causing netfilter modules to fail to load because of the misalignment. (In particular, the first check in net/ipv4/netfilter/ip_tables.c::check_entry_size_and_hooks()) On ppc32 and sparc32, amongst others, __alignof__(uint64_t) == 8. With slab debugging, we use 32-bit redzones. And allocated slab objects aren't sufficiently aligned to hold a structure containing a uint64_t. By _just_ setting ARCH_KMALLOC_MINALIGN to __alignof__(u64) we'd disable redzone checks on those architectures. By using 64-bit redzones we avoid that loss of debugging, and also fix the other problem while we're at it. When investigating this, I noticed that on 64-bit platforms we're using a 32-bit value of RED_ACTIVE/RED_INACTIVE in the 64-bit memory location set aside for the redzone. Which means that the four bytes immediately before or after the allocated object at 0x00,0x00,0x00,0x00 for LE and BE machines, respectively. Which is probably not the most useful choice of poison value. One way to fix both of those at once is just to switch to 64-bit redzones in all cases. Signed-off-by: David Woodhouse <dwmw2@infradead.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* SLUB coreChristoph Lameter2007-05-071-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a new slab allocator which was motivated by the complexity of the existing code in mm/slab.c. It attempts to address a variety of concerns with the existing implementation. A. Management of object queues A particular concern was the complex management of the numerous object queues in SLAB. SLUB has no such queues. Instead we dedicate a slab for each allocating CPU and use objects from a slab directly instead of queueing them up. B. Storage overhead of object queues SLAB Object queues exist per node, per CPU. The alien cache queue even has a queue array that contain a queue for each processor on each node. For very large systems the number of queues and the number of objects that may be caught in those queues grows exponentially. On our systems with 1k nodes / processors we have several gigabytes just tied up for storing references to objects for those queues This does not include the objects that could be on those queues. One fears that the whole memory of the machine could one day be consumed by those queues. C. SLAB meta data overhead SLAB has overhead at the beginning of each slab. This means that data cannot be naturally aligned at the beginning of a slab block. SLUB keeps all meta data in the corresponding page_struct. Objects can be naturally aligned in the slab. F.e. a 128 byte object will be aligned at 128 byte boundaries and can fit tightly into a 4k page with no bytes left over. SLAB cannot do this. D. SLAB has a complex cache reaper SLUB does not need a cache reaper for UP systems. On SMP systems the per CPU slab may be pushed back into partial list but that operation is simple and does not require an iteration over a list of objects. SLAB expires per CPU, shared and alien object queues during cache reaping which may cause strange hold offs. E. SLAB has complex NUMA policy layer support SLUB pushes NUMA policy handling into the page allocator. This means that allocation is coarser (SLUB does interleave on a page level) but that situation was also present before 2.6.13. SLABs application of policies to individual slab objects allocated in SLAB is certainly a performance concern due to the frequent references to memory policies which may lead a sequence of objects to come from one node after another. SLUB will get a slab full of objects from one node and then will switch to the next. F. Reduction of the size of partial slab lists SLAB has per node partial lists. This means that over time a large number of partial slabs may accumulate on those lists. These can only be reused if allocator occur on specific nodes. SLUB has a global pool of partial slabs and will consume slabs from that pool to decrease fragmentation. G. Tunables SLAB has sophisticated tuning abilities for each slab cache. One can manipulate the queue sizes in detail. However, filling the queues still requires the uses of the spin lock to check out slabs. SLUB has a global parameter (min_slab_order) for tuning. Increasing the minimum slab order can decrease the locking overhead. The bigger the slab order the less motions of pages between per CPU and partial lists occur and the better SLUB will be scaling. G. Slab merging We often have slab caches with similar parameters. SLUB detects those on boot up and merges them into the corresponding general caches. This leads to more effective memory use. About 50% of all caches can be eliminated through slab merging. This will also decrease slab fragmentation because partial allocated slabs can be filled up again. Slab merging can be switched off by specifying slub_nomerge on boot up. Note that merging can expose heretofore unknown bugs in the kernel because corrupted objects may now be placed differently and corrupt differing neighboring objects. Enable sanity checks to find those. H. Diagnostics The current slab diagnostics are difficult to use and require a recompilation of the kernel. SLUB contains debugging code that is always available (but is kept out of the hot code paths). SLUB diagnostics can be enabled via the "slab_debug" option. Parameters can be specified to select a single or a group of slab caches for diagnostics. This means that the system is running with the usual performance and it is much more likely that race conditions can be reproduced. I. Resiliency If basic sanity checks are on then SLUB is capable of detecting common error conditions and recover as best as possible to allow the system to continue. J. Tracing Tracing can be enabled via the slab_debug=T,<slabcache> option during boot. SLUB will then protocol all actions on that slabcache and dump the object contents on free. K. On demand DMA cache creation. Generally DMA caches are not needed. If a kmalloc is used with __GFP_DMA then just create this single slabcache that is needed. For systems that have no ZONE_DMA requirement the support is completely eliminated. L. Performance increase Some benchmarks have shown speed improvements on kernbench in the range of 5-10%. The locking overhead of slub is based on the underlying base allocation size. If we can reliably allocate larger order pages then it is possible to increase slub performance much further. The anti-fragmentation patches may enable further performance increases. Tested on: i386 UP + SMP, x86_64 UP + SMP + NUMA emulation, IA64 NUMA + Simulator SLUB Boot options slub_nomerge Disable merging of slabs slub_min_order=x Require a minimum order for slab caches. This increases the managed chunk size and therefore reduces meta data and locking overhead. slub_min_objects=x Mininum objects per slab. Default is 8. slub_max_order=x Avoid generating slabs larger than order specified. slub_debug Enable all diagnostics for all caches slub_debug=<options> Enable selective options for all caches slub_debug=<o>,<cache> Enable selective options for a certain set of caches Available Debug options F Double Free checking, sanity and resiliency R Red zoning P Object / padding poisoning U Track last free / alloc T Trace all allocs / frees (only use for individual slabs). To use SLUB: Apply this patch and then select SLUB as the default slab allocator. [hugh@veritas.com: fix an oops-causing locking error] [akpm@linux-foundation.org: various stupid cleanups and small fixes] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] x86: tighten kernel image page access rightsJan Beulich2007-05-021-3/+0
| | | | | | | | | | | | | | | | | | | | | | | On x86-64, kernel memory freed after init can be entirely unmapped instead of just getting 'poisoned' by overwriting with a debug pattern. On i386 and x86-64 (under CONFIG_DEBUG_RODATA), kernel text and bug table can also be write-protected. Compared to the first version, this one prevents re-creating deleted mappings in the kernel image range on x86-64, if those got removed previously. This, together with the original changes, prevents temporarily having inconsistent mappings when cacheability attributes are being changed on such pages (e.g. from AGP code). While on i386 such duplicate mappings don't exist, the same change is done there, too, both for consistency and because checking pte_present() before using various other pte_XXX functions is a requirement anyway. At once, i386 code gets adjusted to use pte_huge() instead of open coding this. AK: split out cpa() changes Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de>
* [ATM]: add+use poison definesRandy Dunlap2006-07-031-0/+1
| | | | | | | ATM: add and use POISON define values. Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* [NET]: add+use poison definesRandy Dunlap2006-07-031-0/+4
| | | | | | | Add and use poison defines in net/. Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* [PATCH] poison: add & use more constantsRandy Dunlap2006-06-271-0/+7
| | | | | | | | | | | | | | | | Add more poison values to include/linux/poison.h. It's not clear to me whether some others should be added or not, so I haven't added any of these: ./include/linux/libata.h:#define ATA_TAG_POISON 0xfafbfcfdU ./arch/ppc/8260_io/fcc_enet.c:1918: memset((char *)(&(immap->im_dprambase[(mem_addr+64)])), 0x88, 32); ./drivers/usb/mon/mon_text.c:429: memset(mem, 0xe5, sizeof(struct mon_event_text)); ./drivers/char/ftape/lowlevel/ftape-ctl.c:738: memset(ft_buffer[i]->address, 0xAA, FT_BUFF_SIZE); ./drivers/block/sx8.c:/* 0xf is just arbitrary, non-zero noise; this is sorta like poisoning */ Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] update two drivers for poison.hRandy Dunlap2006-06-271-0/+6
| | | | | | | | Update two drivers to use poison.h. Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] add poison.h and patch primary usersRandy Dunlap2006-06-271-0/+45
Localize poison values into one header file for better documentation and easier/quicker debugging and so that the same values won't be used for multiple purposes. Use these constants in core arch., mm, driver, and fs code. Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Acked-by: Matt Mackall <mpm@selenic.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>