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2008-08-09Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: SLUB: dynamic per-cache MIN_PARTIAL mm: unexport ksize
2008-08-06Revert duplicate "mm/hugetlb.c must #include <asm/io.h>"Linus Torvalds
This reverts commit 7cb93181629c613ee2b8f4ffe3446f8003074842, since we did that patch twice, and the problem was already fixed earlier by 78a34ae29bf1c9df62a5bd0f0798b6c62a54d520. Reported-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-05mm: fix uninitialized variables for find_vma_prepare callersBenny Halevy
gcc 4.3.0 correctly emits the following warnings. When a vma covering addr is found, find_vma_prepare indeed returns without setting pprev, rb_link, and rb_parent. mm/mmap.c: In function `insert_vm_struct': mm/mmap.c:2085: warning: `rb_parent' may be used uninitialized in this function mm/mmap.c:2085: warning: `rb_link' may be used uninitialized in this function mm/mmap.c:2084: warning: `prev' may be used uninitialized in this function mm/mmap.c: In function `copy_vma': mm/mmap.c:2124: warning: `rb_parent' may be used uninitialized in this function mm/mmap.c:2124: warning: `rb_link' may be used uninitialized in this function mm/mmap.c:2123: warning: `prev' may be used uninitialized in this function mm/mmap.c: In function `do_brk': mm/mmap.c:1951: warning: `rb_parent' may be used uninitialized in this function mm/mmap.c:1951: warning: `rb_link' may be used uninitialized in this function mm/mmap.c:1949: warning: `prev' may be used uninitialized in this function mm/mmap.c: In function `mmap_region': mm/mmap.c:1092: warning: `rb_parent' may be used uninitialized in this function mm/mmap.c:1092: warning: `rb_link' may be used uninitialized in this function mm/mmap.c:1089: warning: `prev' may be used uninitialized in this function Hugh adds: in fact, none of find_vma_prepare's callers use those values when a vma is found to be already covering addr, it's either an error or an occasion to munmap and repeat. Okay, let's quieten the compiler (but I would prefer it if pprev, rb_link and rb_parent were meaningful in that case, rather than whatever's in them from descending the tree). Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: "Ryan Hope" <rmh3093@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-05mm_init.c: avoid ifdef-inside-macro-expansionAndrew Morton
gcc-3.2: mm/mm_init.c:77:1: directives may not be used inside a macro argument mm/mm_init.c:76:47: unterminated argument list invoking macro "mminit_dprintk" mm/mm_init.c: In function `mminit_verify_pageflags_layout': mm/mm_init.c:80: `mminit_dprintk' undeclared (first use in this function) mm/mm_init.c:80: (Each undeclared identifier is reported only once mm/mm_init.c:80: for each function it appears in.) mm/mm_init.c:80: syntax error before numeric constant Also fix a typo in a comment. Reported-by: Adrian Bunk <bunk@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-05SLUB: dynamic per-cache MIN_PARTIALPekka Enberg
This patch changes the static MIN_PARTIAL to a dynamic per-cache ->min_partial value that is calculated from object size. The bigger the object size, the more pages we keep on the partial list. I tested SLAB, SLUB, and SLUB with this patch on Jens Axboe's 'netio' example script of the fio benchmarking tool. The script stresses the networking subsystem which should also give a fairly good beating of kmalloc() et al. To run the test yourself, first clone the fio repository: git clone git://git.kernel.dk/fio.git and then run the following command n times on your machine: time ./fio examples/netio The results on my 2-way 64-bit x86 machine are as follows: [ the minimum, maximum, and average are captured from 50 individual runs ] real time (seconds) min max avg sd SLAB 22.76 23.38 22.98 0.17 SLUB 22.80 25.78 23.46 0.72 SLUB (dynamic) 22.74 23.54 23.00 0.20 sys time (seconds) min max avg sd SLAB 6.90 8.28 7.70 0.28 SLUB 7.42 16.95 8.89 2.28 SLUB (dynamic) 7.17 8.64 7.73 0.29 user time (seconds) min max avg sd SLAB 36.89 38.11 37.50 0.29 SLUB 30.85 37.99 37.06 1.67 SLUB (dynamic) 36.75 38.07 37.59 0.32 As you can see from the above numbers, this patch brings SLUB to the same level as SLAB for this particular workload fixing a ~2% regression. I'd expect this change to help similar workloads that allocate a lot of objects that are close to the size of a page. Cc: Matthew Wilcox <matthew@wil.cx> Cc: Andrew Morton <akpm@linux-foundation.org> Acked-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2008-08-04mm: rename page trylockNick Piggin
Converting page lock to new locking bitops requires a change of page flag operation naming, so we might as well convert it to something nicer (!TestSetPageLocked_Lock => trylock_page, SetPageLocked => set_page_locked). This also facilitates lockdeping of page lock. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-04Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (29 commits) sh: enable maple_keyb in dreamcast_defconfig. SH2(A) cache update nommu: Provide vmalloc_exec(). add addrespace definition for sh2a. sh: Kill off ARCH_SUPPORTS_AOUT and remnants of a.out support. sh: define GENERIC_HARDIRQS_NO__DO_IRQ. sh: define GENERIC_LOCKBREAK. sh: Save NUMA node data in vmcore for crash dumps. sh: module_alloc() should be using vmalloc_exec(). sh: Fix up __bug_table handling in module loader. sh: Add documentation and integrate into docbook build. sh: Fix up broken kerneldoc comments. maple: Kill useless private_data pointer. maple: Clean up maple_driver_register/unregister routines. input: Clean up maple keyboard driver maple: allow removal and reinsertion of keyboard driver module sh: /proc/asids depends on MMU. arch/sh/boards/mach-se/7343/irq.c: removed duplicated #include arch/sh/boards/board-ap325rxa.c: removed duplicated #include sh/boards/Makefile typo fix ...
2008-08-04mlock() fix return valuesKOSAKI Motohiro
Halesh says: Please find the below testcase provide to test mlock. Test Case : =========================== #include <sys/resource.h> #include <stdio.h> #include <sys/stat.h> #include <sys/types.h> #include <unistd.h> #include <sys/mman.h> #include <fcntl.h> #include <errno.h> #include <stdlib.h> int main(void) { int fd,ret, i = 0; char *addr, *addr1 = NULL; unsigned int page_size; struct rlimit rlim; if (0 != geteuid()) { printf("Execute this pgm as root\n"); exit(1); } /* create a file */ if ((fd = open("mmap_test.c",O_RDWR|O_CREAT,0755)) == -1) { printf("cant create test file\n"); exit(1); } page_size = sysconf(_SC_PAGE_SIZE); /* set the MEMLOCK limit */ rlim.rlim_cur = 2000; rlim.rlim_max = 2000; if ((ret = setrlimit(RLIMIT_MEMLOCK,&rlim)) != 0) { printf("Cant change limit values\n"); exit(1); } addr = 0; while (1) { /* map a page into memory each time*/ if ((addr = (char *) mmap(addr,page_size, PROT_READ | PROT_WRITE,MAP_SHARED,fd,0)) == MAP_FAILED) { printf("cant do mmap on file\n"); exit(1); } if (0 == i) addr1 = addr; i++; errno = 0; /* lock the mapped memory pagewise*/ if ((ret = mlock((char *)addr, 1500)) == -1) { printf("errno value is %d\n", errno); printf("cant lock maped region\n"); exit(1); } addr = addr + page_size; } } ====================================================== This testcase results in an mlock() failure with errno 14 that is EFAULT, but it has nowhere been specified that mlock() will return EFAULT. When I tested the same on older kernels like 2.6.18, I got the correct result i.e errno 12 (ENOMEM). I think in source code mlock(2), setting errno ENOMEM has been missed in do_mlock() , on mlock_fixup() failure. SUSv3 requires the following behavior frmo mlock(2). [ENOMEM] Some or all of the address range specified by the addr and len arguments does not correspond to valid mapped pages in the address space of the process. [EAGAIN] Some or all of the memory identified by the operation could not be locked when the call was made. This rule isn't so nice and slighly strange. but many people think POSIX/SUS compliance is important. Reported-by: Halesh Sadashiv <halesh.sadashiv@ap.sony.com> Tested-by: Halesh Sadashiv <halesh.sadashiv@ap.sony.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-04nommu: Provide vmalloc_exec().Paul Mundt
Now that SH has switched to vmalloc_exec() for PAGE_KERNEL_EXEC usage, it's apparent that nommu has no vmalloc_exec() definition of its own. Stub in the one from mm/vmalloc.c. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-08-02mm: dont clear PG_uptodate on truncate/invalidateMiklos Szeredi
Brian Wang reported that a FUSE filesystem exported through NFS could return I/O errors on read. This was traced to splice_direct_to_actor() returning a short or zero count when racing with page invalidation. However this is not FUSE or NFSD specific, other filesystems (notably NFS) also call invalidate_inode_pages2() to purge stale data from the cache. If this happens while such pages are sitting in a pipe buffer, then splice(2) from the pipe can return zero, and read(2) from the pipe can return ENODATA. The zero return is especially bad, since it implies end-of-file or disconnected pipe/socket, and is documented as such for splice. But returning an error for read() is also nasty, when in fact there was no error (data becoming stale is not an error). The same problems can be triggered by "hole punching" with madvise(MADV_REMOVE). Fix this by not clearing the PG_uptodate flag on truncation and invalidation. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-01Remove EXPORTS of follow_page & zap_page_rangeJack Steiner
Delete 2 EXPORTs that were accidentally sent upstream. Signed-off-by: Jack Steiner <steiner@sgi.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-01mm/hugetlb: don't crash when HPAGE_SHIFT is 0Benjamin Herrenschmidt
Some platform decide whether they support huge pages at boot time. On these, such as powerpc, HPAGE_SHIFT is a variable, not a constant, and is set to 0 when there is no such support. The patches to introduce multiple huge pages support broke that causing the kernel to crash at boot time on machines such as POWER3 which lack support for multiple page sizes. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-08-01Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (28 commits) mm/hugetlb.c must #include <asm/io.h> video: Fix up hp6xx driver build regressions. sh: defconfig updates. sh: Kill off stray mach-rsk7203 reference. serial: sh-sci: Fix up SH7760/SH7780/SH7785 early printk regression. sh: Move out individual boards without mach groups. sh: Make sure AT_SYSINFO_EHDR is exposed to userspace in asm/auxvec.h. sh: Allow SH-3 and SH-5 to use common headers. sh: Provide common CPU headers, prune the SH-2 and SH-2A directories. sh/maple: clean maple bus code sh: More header path fixups for mach dir refactoring. sh: Move out the solution engine headers to arch/sh/include/mach-se/ sh: I2C fix for AP325RXA and Migo-R sh: Shuffle the board directories in to mach groups. sh: dma-sh: Fix up dreamcast dma.h mach path. sh: Switch KBUILD_DEFCONFIG to shx3_defconfig. sh: Add ARCH_DEFCONFIG entries for sh and sh64. sh: Fix compile error of Solution Engine sh: Proper __put_user_asm() size mismatch fix. sh: Stub in a dummy ENTRY_OFFSET for uImage offset calculation. ...
2008-08-01[S390] Optimize storage key operations for anon pagesMartin Schwidefsky
For anonymous pages without a swap cache backing the check in page_remove_rmap for the physical dirty bit in page_remove_rmap is unnecessary. The instructions that are used to check and reset the dirty bit are expensive. Removing the check noticably speeds up process exit. In addition the clearing of the dirty bit in __SetPageUptodate is pointless as well. With these two changes there is no storage key operation for an anonymous page anymore if it does not hit the swap space. The micro benchmark which repeatedly executes an empty shell script gets about 5% faster. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-07-30Fix off-by-one error in iov_iter_advance()Linus Torvalds
The iov_iter_advance() function would look at the iov->iov_len entry even though it might have iterated over the whole array, and iov was pointing past the end. This would cause DEBUG_PAGEALLOC to trigger a kernel page fault if the allocation was at the end of a page, and the next page was unallocated. The quick fix is to just change the order of the tests: check that there is any iovec data left before we check the iov entry itself. Thanks to Alexey Dobriyan for finding this case, and testing the fix. Reported-and-tested-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30GRU Driver: export is_uv_system(), zap_page_range() & follow_page()Jack Steiner
Exports needed by the GRU driver. Signed-off-by: Jack Steiner <steiner@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30mm: add zap_vma_ptes(): a library function to unmap driver ptesJack Steiner
zap_vma_ptes() is intended to be used by drivers to unmap ptes assigned to the driver private vmas. This interface is similar to zap_page_range() but is less general & less likely to be abused. Needed by the GRU driver. Signed-off-by: Jack Steiner <steiner@sgi.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30do_try_to_free_page: update comments related to vmscan functionsFernando Luis Vazquez Cao
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30swapfile/vmscan: update comments related to vmscan functionsFernando Luis Vazquez Cao
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30swap: update function comment of release_pagesFernando Luis Vazquez Cao
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30madvise: update function comment of madvise_dontneedFernando Luis Vazquez Cao
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30memcg: remove redundant check in move_task()Li Zefan
It's guaranteed by cgroup that old_cgrp != cgrp. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-30mm: remove find_max_pfn_with_active_regionsYinghai Lu
It has no user now Also print out info about adding/removing active regions. Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-29mm: unexport ksizeAdrian Bunk
This patch removes the obsolete and no longer used exports of ksize. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2008-07-30mm/hugetlb.c must #include <asm/io.h>Adrian Bunk
This patch fixes the following build error on sh caused by commit aa888a74977a8f2120ae9332376e179c39a6b07d (hugetlb: support larger than MAX_ORDER): <-- snip --> ... CC mm/hugetlb.o /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/hugetlb.c: In function 'alloc_bootmem_huge_page': /home/bunk/linux/kernel-2.6/git/linux-2.6/mm/hugetlb.c:958: error: implicit declaration of function 'virt_to_phys' make[2]: *** [mm/hugetlb.o] Error 1 <-- snip --> Reported-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-07-28vfs: pagecache usage optimization for pagesize!=blocksizeHisashi Hifumi
When we read some part of a file through pagecache, if there is a pagecache of corresponding index but this page is not uptodate, read IO is issued and this page will be uptodate. I think this is good for pagesize == blocksize environment but there is room for improvement on pagesize != blocksize environment. Because in this case a page can have multiple buffers and even if a page is not uptodate, some buffers can be uptodate. So I suggest that when all buffers which correspond to a part of a file that we want to read are uptodate, use this pagecache and copy data from this pagecache to user buffer even if a page is not uptodate. This can reduce read IO and improve system throughput. I wrote a benchmark program and got result number with this program. This benchmark do: 1: mount and open a test file. 2: create a 512MB file. 3: close a file and umount. 4: mount and again open a test file. 5: pwrite randomly 300000 times on a test file. offset is aligned by IO size(1024bytes). 6: measure time of preading randomly 100000 times on a test file. The result was: 2.6.26 330 sec 2.6.26-patched 226 sec Arch:i386 Filesystem:ext3 Blocksize:1024 bytes Memory: 1GB On ext3/4, a file is written through buffer/block. So random read/write mixed workloads or random read after random write workloads are optimized with this patch under pagesize != blocksize environment. This test result showed this. The benchmark program is as follows: #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <time.h> #include <stdlib.h> #include <string.h> #include <sys/mount.h> #define LEN 1024 #define LOOP 1024*512 /* 512MB */ main(void) { unsigned long i, offset, filesize; int fd; char buf[LEN]; time_t t1, t2; if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) { perror("cannot mount\n"); exit(1); } memset(buf, 0, LEN); fd = open("/root/test1/testfile", O_CREAT|O_RDWR|O_TRUNC); if (fd < 0) { perror("cannot open file\n"); exit(1); } for (i = 0; i < LOOP; i++) write(fd, buf, LEN); close(fd); if (umount("/root/test1/") < 0) { perror("cannot umount\n"); exit(1); } if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) { perror("cannot mount\n"); exit(1); } fd = open("/root/test1/testfile", O_RDWR); if (fd < 0) { perror("cannot open file\n"); exit(1); } filesize = LEN * LOOP; for (i = 0; i < 300000; i++){ offset = (random() % filesize) & (~(LEN - 1)); pwrite(fd, buf, LEN, offset); } printf("start test\n"); time(&t1); for (i = 0; i < 100000; i++){ offset = (random() % filesize) & (~(LEN - 1)); pread(fd, buf, LEN, offset); } time(&t2); printf("%ld sec\n", t2-t1); close(fd); if (umount("/root/test1/") < 0) { perror("cannot umount\n"); exit(1); } } Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Hellwig <hch@infradead.org> Cc: Jan Kara <jack@ucw.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28mm/hugetlb.c must #include <asm/io.h>Adrian Bunk
This patch fixes the following build error on sh caused by commit aa888a74977a8f2120ae9332376e179c39a6b07d ("hugetlb: support larger than MAX_ORDER"): mm/hugetlb.c: In function 'alloc_bootmem_huge_page': mm/hugetlb.c:958: error: implicit declaration of function 'virt_to_phys' Signed-off-by: Adrian Bunk <bunk@kernel.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28mmu-notifiers: coreAndrea Arcangeli
With KVM/GFP/XPMEM there isn't just the primary CPU MMU pointing to pages. There are secondary MMUs (with secondary sptes and secondary tlbs) too. sptes in the kvm case are shadow pagetables, but when I say spte in mmu-notifier context, I mean "secondary pte". In GRU case there's no actual secondary pte and there's only a secondary tlb because the GRU secondary MMU has no knowledge about sptes and every secondary tlb miss event in the MMU always generates a page fault that has to be resolved by the CPU (this is not the case of KVM where the a secondary tlb miss will walk sptes in hardware and it will refill the secondary tlb transparently to software if the corresponding spte is present). The same way zap_page_range has to invalidate the pte before freeing the page, the spte (and secondary tlb) must also be invalidated before any page is freed and reused. Currently we take a page_count pin on every page mapped by sptes, but that means the pages can't be swapped whenever they're mapped by any spte because they're part of the guest working set. Furthermore a spte unmap event can immediately lead to a page to be freed when the pin is released (so requiring the same complex and relatively slow tlb_gather smp safe logic we have in zap_page_range and that can be avoided completely if the spte unmap event doesn't require an unpin of the page previously mapped in the secondary MMU). The mmu notifiers allow kvm/GRU/XPMEM to attach to the tsk->mm and know when the VM is swapping or freeing or doing anything on the primary MMU so that the secondary MMU code can drop sptes before the pages are freed, avoiding all page pinning and allowing 100% reliable swapping of guest physical address space. Furthermore it avoids the code that teardown the mappings of the secondary MMU, to implement a logic like tlb_gather in zap_page_range that would require many IPI to flush other cpu tlbs, for each fixed number of spte unmapped. To make an example: if what happens on the primary MMU is a protection downgrade (from writeable to wrprotect) the secondary MMU mappings will be invalidated, and the next secondary-mmu-page-fault will call get_user_pages and trigger a do_wp_page through get_user_pages if it called get_user_pages with write=1, and it'll re-establishing an updated spte or secondary-tlb-mapping on the copied page. Or it will setup a readonly spte or readonly tlb mapping if it's a guest-read, if it calls get_user_pages with write=0. This is just an example. This allows to map any page pointed by any pte (and in turn visible in the primary CPU MMU), into a secondary MMU (be it a pure tlb like GRU, or an full MMU with both sptes and secondary-tlb like the shadow-pagetable layer with kvm), or a remote DMA in software like XPMEM (hence needing of schedule in XPMEM code to send the invalidate to the remote node, while no need to schedule in kvm/gru as it's an immediate event like invalidating primary-mmu pte). At least for KVM without this patch it's impossible to swap guests reliably. And having this feature and removing the page pin allows several other optimizations that simplify life considerably. Dependencies: 1) mm_take_all_locks() to register the mmu notifier when the whole VM isn't doing anything with "mm". This allows mmu notifier users to keep track if the VM is in the middle of the invalidate_range_begin/end critical section with an atomic counter incraese in range_begin and decreased in range_end. No secondary MMU page fault is allowed to map any spte or secondary tlb reference, while the VM is in the middle of range_begin/end as any page returned by get_user_pages in that critical section could later immediately be freed without any further ->invalidate_page notification (invalidate_range_begin/end works on ranges and ->invalidate_page isn't called immediately before freeing the page). To stop all page freeing and pagetable overwrites the mmap_sem must be taken in write mode and all other anon_vma/i_mmap locks must be taken too. 2) It'd be a waste to add branches in the VM if nobody could possibly run KVM/GRU/XPMEM on the kernel, so mmu notifiers will only enabled if CONFIG_KVM=m/y. In the current kernel kvm won't yet take advantage of mmu notifiers, but this already allows to compile a KVM external module against a kernel with mmu notifiers enabled and from the next pull from kvm.git we'll start using them. And GRU/XPMEM will also be able to continue the development by enabling KVM=m in their config, until they submit all GRU/XPMEM GPLv2 code to the mainline kernel. Then they can also enable MMU_NOTIFIERS in the same way KVM does it (even if KVM=n). This guarantees nobody selects MMU_NOTIFIER=y if KVM and GRU and XPMEM are all =n. The mmu_notifier_register call can fail because mm_take_all_locks may be interrupted by a signal and return -EINTR. Because mmu_notifier_reigster is used when a driver startup, a failure can be gracefully handled. Here an example of the change applied to kvm to register the mmu notifiers. Usually when a driver startups other allocations are required anyway and -ENOMEM failure paths exists already. struct kvm *kvm_arch_create_vm(void) { struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL); + int err; if (!kvm) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); + kvm->arch.mmu_notifier.ops = &kvm_mmu_notifier_ops; + err = mmu_notifier_register(&kvm->arch.mmu_notifier, current->mm); + if (err) { + kfree(kvm); + return ERR_PTR(err); + } + return kvm; } mmu_notifier_unregister returns void and it's reliable. The patch also adds a few needed but missing includes that would prevent kernel to compile after these changes on non-x86 archs (x86 didn't need them by luck). [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix mm/filemap_xip.c build] [akpm@linux-foundation.org: fix mm/mmu_notifier.c build] Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Cc: Jack Steiner <steiner@sgi.com> Cc: Robin Holt <holt@sgi.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Kanoj Sarcar <kanojsarcar@yahoo.com> Cc: Roland Dreier <rdreier@cisco.com> Cc: Steve Wise <swise@opengridcomputing.com> Cc: Avi Kivity <avi@qumranet.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Chris Wright <chrisw@redhat.com> Cc: Marcelo Tosatti <marcelo@kvack.org> Cc: Eric Dumazet <dada1@cosmosbay.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Izik Eidus <izike@qumranet.com> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28mmu-notifiers: add mm_take_all_locks() operationAndrea Arcangeli
mm_take_all_locks holds off reclaim from an entire mm_struct. This allows mmu notifiers to register into the mm at any time with the guarantee that no mmu operation is in progress on the mm. This operation locks against the VM for all pte/vma/mm related operations that could ever happen on a certain mm. This includes vmtruncate, try_to_unmap, and all page faults. The caller must take the mmap_sem in write mode before calling mm_take_all_locks(). The caller isn't allowed to release the mmap_sem until mm_drop_all_locks() returns. mmap_sem in write mode is required in order to block all operations that could modify pagetables and free pages without need of altering the vma layout (for example populate_range() with nonlinear vmas). It's also needed in write mode to avoid new anon_vmas to be associated with existing vmas. A single task can't take more than one mm_take_all_locks() in a row or it would deadlock. mm_take_all_locks() and mm_drop_all_locks are expensive operations that may have to take thousand of locks. mm_take_all_locks() can fail if it's interrupted by signals. When mmu_notifier_register returns, we must be sure that the driver is notified if some task is in the middle of a vmtruncate for the 'mm' where the mmu notifier was registered (mmu_notifier_invalidate_range_start/end is run around the vmtruncation but mmu_notifier_register can run after mmu_notifier_invalidate_range_start and before mmu_notifier_invalidate_range_end). Same problem for rmap paths. And we've to remove page pinning to avoid replicating the tlb_gather logic inside KVM (and GRU doesn't work well with page pinning regardless of needing tlb_gather), so without mm_take_all_locks when vmtruncate frees the page, kvm would have no way to notice that it mapped into sptes a page that is going into the freelist without a chance of any further mmu_notifier notification. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Jack Steiner <steiner@sgi.com> Cc: Robin Holt <holt@sgi.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Kanoj Sarcar <kanojsarcar@yahoo.com> Cc: Roland Dreier <rdreier@cisco.com> Cc: Steve Wise <swise@opengridcomputing.com> Cc: Avi Kivity <avi@qumranet.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Chris Wright <chrisw@redhat.com> Cc: Marcelo Tosatti <marcelo@kvack.org> Cc: Eric Dumazet <dada1@cosmosbay.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Izik Eidus <izike@qumranet.com> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28tmpfs: fix kernel BUG in shmem_delete_inodeHugh Dickins
SuSE's insserve initscript ordering program hits kernel BUG at mm/shmem.c:814 on 2.6.26. It's using posix_fadvise on directories, and the shmem_readpage method added in 2.6.23 is letting POSIX_FADV_WILLNEED allocate useless pages to a tmpfs directory, incrementing i_blocks count but never decrementing it. Fix this by assigning shmem_aops (pointing to readpage and writepage and set_page_dirty) only when it's needed, on a regular file or a long symlink. Many thanks to Kel for outstanding bugreport and steps to reproduce it. Reported-by: Kel Modderman <kel@otaku42.de> Tested-by: Kel Modderman <kel@otaku42.de> Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-28stop_machine: Wean existing callers off stop_machine_run()Rusty Russell
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-26Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (39 commits) [PATCH] fix RLIM_NOFILE handling [PATCH] get rid of corner case in dup3() entirely [PATCH] remove remaining namei_{32,64}.h crap [PATCH] get rid of indirect users of namei.h [PATCH] get rid of __user_path_lookup_open [PATCH] f_count may wrap around [PATCH] dup3 fix [PATCH] don't pass nameidata to __ncp_lookup_validate() [PATCH] don't pass nameidata to gfs2_lookupi() [PATCH] new (local) helper: user_path_parent() [PATCH] sanitize __user_walk_fd() et.al. [PATCH] preparation to __user_walk_fd cleanup [PATCH] kill nameidata passing to permission(), rename to inode_permission() [PATCH] take noexec checks to very few callers that care Re: [PATCH 3/6] vfs: open_exec cleanup [patch 4/4] vfs: immutable inode checking cleanup [patch 3/4] fat: dont call notify_change [patch 2/4] vfs: utimes cleanup [patch 1/4] vfs: utimes: move owner check into inode_change_ok() [PATCH] vfs: use kstrdup() and check failing allocation ...
2008-07-26Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: netns: fix ip_rt_frag_needed rt_is_expired netfilter: nf_conntrack_extend: avoid unnecessary "ct->ext" dereferences netfilter: fix double-free and use-after free netfilter: arptables in netns for real netfilter: ip{,6}tables_security: fix future section mismatch selinux: use nf_register_hooks() netfilter: ebtables: use nf_register_hooks() Revert "pkt_sched: sch_sfq: dump a real number of flows" qeth: use dev->ml_priv instead of dev->priv syncookies: Make sure ECN is disabled net: drop unused BUG_TRAP() net: convert BUG_TRAP to generic WARN_ON drivers/net: convert BUG_TRAP to generic WARN_ON
2008-07-26mm/util.c must #include <linux/sched.h>Adrian Bunk
mm/util.c: In function 'arch_pick_mmap_layout': mm/util.c:144: error: dereferencing pointer to incomplete type mm/util.c:145: error: 'arch_get_unmapped_area' undeclared (first use in this function) mm/util.c:145: error: (Each undeclared identifier is reported only once mm/util.c:145: error: for each function it appears in.) mm/util.c:146: error: 'arch_unmap_area' undeclared (first use in this function) Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26[patch 3/5] vfs: change remove_suid() to file_remove_suid()Miklos Szeredi
All calls to remove_suid() are made with a file pointer, because (similarly to file_update_time) it is called when the file is written. Clean up callers by passing in a file instead of a dentry. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2008-07-26[PATCH] sanitize ->permission() prototypeAl Viro
* kill nameidata * argument; map the 3 bits in ->flags anybody cares about to new MAY_... ones and pass with the mask. * kill redundant gfs2_iop_permission() * sanitize ecryptfs_permission() * fix remaining places where ->permission() instances might barf on new MAY_... found in mask. The obvious next target in that direction is permission(9) folded fix for nfs_permission() breakage from Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-07-26netfilter: fix double-free and use-after freePekka Enberg
As suggested by Patrick McHardy, introduce a __krealloc() that doesn't free the original buffer to fix a double-free and use-after-free bug introduced by me in netfilter that uses RCU. Reported-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Tested-by: Dieter Ries <clip2@gmx.de> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-26mm/swapfile.c: make code staticAdrian Bunk
This patch makes the following needlessly global code static: - swap_lock - nr_swapfiles - struct swap_list Signed-off-by: Adrian Bunk <bunk@kernel.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26make mm/memory.c:print_bad_pte() staticAdrian Bunk
This patch makes the needlessly global print_bad_pte() static. Signed-off-by: Adrian Bunk <bunk@kernel.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26mm/allocpercpu.c: make 4 functions staticAdrian Bunk
This patch makes the following needlessly global functions static: - percpu_depopulate() - __percpu_depopulate_mask() - percpu_populate() - __percpu_populate_mask() Signed-off-by: Adrian Bunk <bunk@kernel.org> Acked-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26make mm/sparse.c: make a function staticAdrian Bunk
This patch makes the needlessly global sparse_early_mem_map_alloc() static. Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26mm: print swapcache page count in show_swap_cache_info()Johannes Weiner
Every arch implements its own show_mem() function. Most of them share quite some code, some of them are completely identical. This series implements a generic version of this function and migrates almost all architectures to it. This patch: Most show_mem() implementations calculate the amount of pages within the swapcache every time. Move the output to a more appropriate place and use the anyway available total_swapcache_pages variable. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Bryan Wu <cooloney@kernel.org> Cc: Chris Zankel <chris@zankel.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jeff Dike <jdike@addtoit.com> Cc: David S. Miller <davem@davemloft.net> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Greg Ungerer <gerg@uclinux.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: Mikael Starvik <starvik@axis.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26tracehook: tracehook_expect_breakpointsRoland McGrath
This adds tracehook_expect_breakpoints() as a formal hook for the nommu code to use for its, "Is text-poking likely?" check at mmap time. This names the actual semantics the code means to test, and documents it. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Reviewed-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26Use WARN() in mm/vmalloc.cArjan van de Ven
Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26SL*B: drop kmem cache argument from constructorAlexey Dobriyan
Kmem cache passed to constructor is only needed for constructors that are themselves multiplexeres. Nobody uses this "feature", nor does anybody uses passed kmem cache in non-trivial way, so pass only pointer to object. Non-trivial places are: arch/powerpc/mm/init_64.c arch/powerpc/mm/hugetlbpage.c This is flag day, yes. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by: Christoph Lameter <cl@linux-foundation.org> Cc: Jon Tollefson <kniht@linux.vnet.ibm.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Matt Mackall <mpm@selenic.com> [akpm@linux-foundation.org: fix arch/powerpc/mm/hugetlbpage.c] [akpm@linux-foundation.org: fix mm/slab.c] [akpm@linux-foundation.org: fix ubifs] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26mm: spinlock tree_lockNick Piggin
mapping->tree_lock has no read lockers. convert the lock from an rwlock to a spinlock. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26mm: lockless pagecacheNick Piggin
Combine page_cache_get_speculative with lockless radix tree lookups to introduce lockless page cache lookups (ie. no mapping->tree_lock on the read-side). The only atomicity changes this introduces is that the gang pagecache lookup functions now behave as if they are implemented with multiple find_get_page calls, rather than operating on a snapshot of the pages. In practice, this atomicity guarantee is not used anyway, and it is to replace individual lookups, so these semantics are natural. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26mm: speculative page referencesNick Piggin
If we can be sure that elevating the page_count on a pagecache page will pin it, we can speculatively run this operation, and subsequently check to see if we hit the right page rather than relying on holding a lock or otherwise pinning a reference to the page. This can be done if get_page/put_page behaves consistently throughout the whole tree (ie. if we "get" the page after it has been used for something else, we must be able to free it with a put_page). Actually, there is a period where the count behaves differently: when the page is free or if it is a constituent page of a compound page. We need an atomic_inc_not_zero operation to ensure we don't try to grab the page in either case. This patch introduces the core locking protocol to the pagecache (ie. adds page_cache_get_speculative, and tweaks some update-side code to make it work). Thanks to Hugh for pointing out an improvement to the algorithm setting page_count to zero when we have control of all references, in order to hold off speculative getters. [kamezawa.hiroyu@jp.fujitsu.com: fix migration_entry_wait()] [hugh@veritas.com: fix add_to_page_cache] [akpm@linux-foundation.org: repair a comment] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Jeff Garzik <jeff@garzik.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26mm: readahead scan locklessNick Piggin
radix_tree_next_hole() is implemented as a series of radix_tree_lookup()s. So it can be called locklessly, under rcu_read_lock(). Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-26x86: lockless get_user_pages_fast()Nick Piggin
Implement get_user_pages_fast without locking in the fastpath on x86. Do an optimistic lockless pagetable walk, without taking mmap_sem or any page table locks or even mmap_sem. Page table existence is guaranteed by turning interrupts off (combined with the fact that we're always looking up the current mm, means we can do the lockless page table walk within the constraints of the TLB shootdown design). Basically we can do this lockless pagetable walk in a similar manner to the way the CPU's pagetable walker does not have to take any locks to find present ptes. This patch (combined with the subsequent ones to convert direct IO to use it) was found to give about 10% performance improvement on a 2 socket 8 core Intel Xeon system running an OLTP workload on DB2 v9.5 "To test the effects of the patch, an OLTP workload was run on an IBM x3850 M2 server with 2 processors (quad-core Intel Xeon processors at 2.93 GHz) using IBM DB2 v9.5 running Linux 2.6.24rc7 kernel. Comparing runs with and without the patch resulted in an overall performance benefit of ~9.8%. Correspondingly, oprofiles showed that samples from __up_read and __down_read routines that is seen during thread contention for system resources was reduced from 2.8% down to .05%. Monitoring the /proc/vmstat output from the patched run showed that the counter for fast_gup contained a very high number while the fast_gup_slow value was zero." (fast_gup is the old name for get_user_pages_fast, fast_gup_slow is a counter we had for the number of times the slowpath was invoked). The main reason for the improvement is that DB2 has multiple threads each issuing direct-IO. Direct-IO uses get_user_pages, and thus the threads contend the mmap_sem cacheline, and can also contend on page table locks. I would anticipate larger performance gains on larger systems, however I think DB2 uses an adaptive mix of threads and processes, so it could be that thread contention remains pretty constant as machine size increases. In which case, we stuck with "only" a 10% gain. The downside of using get_user_pages_fast is that if there is not a pte with the correct permissions for the access, we end up falling back to get_user_pages and so the get_user_pages_fast is a bit of extra work. However this should not be the common case in most performance critical code. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: build fix] [akpm@linux-foundation.org: Kconfig fix] [akpm@linux-foundation.org: Makefile fix/cleanup] [akpm@linux-foundation.org: warning fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Zach Brown <zach.brown@oracle.com> Cc: Jens Axboe <jens.axboe@oracle.com> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>