linux/Documentation/vm, branch v4.0

mm:add KPF_ZERO_PAGE flag for /proc/kpageflags

2015-02-12T01:06:00Z

Add KPF_ZERO_PAGE flag for zero_page, so that userspace processes can detect zero_page in /proc/kpageflags, and then do memory analysis more accurately. Signed-off-by: Yalin Wang Acked-by: Kirill A. Shutemov Cc: Konstantin Khlebnikov Cc: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2015-02-11T02:57:15Z

Pull trivial tree changes from Jiri Kosina: "Patches from trivial.git that keep the world turning around. Mostly documentation and comment fixes, and a two corner-case code fixes from Alan Cox" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: kexec, Kconfig: spell "architecture" properly mm: fix cleancache debugfs directory path blackfin: mach-common: ints-priority: remove unused function doubletalk: probe failure causes OOPS ARM: cache-l2x0.c: Make it clear that cache-l2x0 handles L310 cache controller msdos_fs.h: fix 'fields' in comment scsi: aic7xxx: fix comment ARM: l2c: fix comment ibmraid: fix writeable attribute with no store method dynamic_debug: fix comment doc: usbmon: fix spelling s/unpriviledged/unprivileged/ x86: init_mem_mapping(): use capital BIOS in comment

mm: replace remap_file_pages() syscall with emulation

2015-02-10T22:30:30Z

remap_file_pages(2) was invented to be able efficiently map parts of huge file into limited 32-bit virtual address space such as in database workloads. Nonlinear mappings are pain to support and it seems there's no legitimate use-cases nowadays since 64-bit systems are widely available. Let's drop it and get rid of all these special-cased code. The patch replaces the syscall with emulation which creates new VMA on each remap_file_pages(), unless they it can be merged with an adjacent one. I didn't find *any* real code that uses remap_file_pages(2) to test emulation impact on. I've checked Debian code search and source of all packages in ALT Linux. No real users: libc wrappers, mentions in strace, gdb, valgrind and this kind of stuff. There are few basic tests in LTP for the syscall. They work just fine with emulation. To test performance impact, I've written small test case which demonstrate pretty much worst case scenario: map 4G shmfs file, write to begin of every page pgoff of the page, remap pages in reverse order, read every page. The test creates 1 million of VMAs if emulation is in use, so I had to set vm.max_map_count to 1100000 to avoid -ENOMEM. Before: 23.3 ( +- 4.31% ) seconds After: 43.9 ( +- 0.85% ) seconds Slowdown: 1.88x I believe we can live with that. Test case: #define _GNU_SOURCE #include #include #include #include #define MB (1024UL * 1024) #define SIZE (4096 * MB) int main(int argc, char **argv) { unsigned long *p; long i, pass; for (pass = 0; pass < 10; pass++) { p = mmap(NULL, SIZE, PROT_READ|PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) { perror("mmap"); return -1; } for (i = 0; i < SIZE / 4096; i++) p[i * 4096 / sizeof(*p)] = i; for (i = 0; i < SIZE / 4096; i++) { if (remap_file_pages(p + i * 4096 / sizeof(*p), 4096, 0, (SIZE - 4096 * (i + 1)) >> 12, 0)) { perror("remap_file_pages"); return -1; } } for (i = SIZE / 4096 - 1; i >= 0; i--) assert(p[i * 4096 / sizeof(*p)] == SIZE / 4096 - i - 1); munmap(p, SIZE); } return 0; } [akpm@linux-foundation.org: fix spello] [sasha.levin@oracle.com: initialize populate before usage] [sasha.levin@oracle.com: grab file ref to prevent race while mmaping] Signed-off-by: "Kirill A. Shutemov" Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Dave Jones Cc: Linus Torvalds Cc: Armin Rigo Signed-off-by: Sasha Levin Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: fix cleancache debugfs directory path

2015-01-20T13:08:31Z

Minor fixes for cleancache about wrong debugfs paths in documentation and code comment. Signed-off-by: Marcin Jabrzyk Signed-off-by: Jiri Kosina

Merge branch 'akpm' (second patch-bomb from Andrew)

2014-12-13T21:00:36Z

Merge second patchbomb from Andrew Morton: - the rest of MM - misc fs fixes - add execveat() syscall - new ratelimit feature for fault-injection - decompressor updates - ipc/ updates - fallocate feature creep - fsnotify cleanups - a few other misc things * emailed patches from Andrew Morton : (99 commits) cgroups: Documentation: fix trivial typos and wrong paragraph numberings parisc: percpu: update comments referring to __get_cpu_var percpu: update local_ops.txt to reflect this_cpu operations percpu: remove __get_cpu_var and __raw_get_cpu_var macros fsnotify: remove destroy_list from fsnotify_mark fsnotify: unify inode and mount marks handling fallocate: create FAN_MODIFY and IN_MODIFY events mm/cma: make kmemleak ignore CMA regions slub: fix cpuset check in get_any_partial slab: fix cpuset check in fallback_alloc shmdt: use i_size_read() instead of ->i_size ipc/shm.c: fix overly aggressive shmdt() when calls span multiple segments ipc/msg: increase MSGMNI, remove scaling ipc/sem.c: increase SEMMSL, SEMMNI, SEMOPM ipc/sem.c: change memory barrier in sem_lock() to smp_rmb() lib/decompress.c: consistency of compress formats for kernel image decompress_bunzip2: off by one in get_next_block() usr/Kconfig: make initrd compression algorithm selection not expert fault-inject: add ratelimit option ratelimit: add initialization macro ...

Documentation: add new page_owner document

2014-12-13T20:42:48Z

page owner is for the tracking about who allocated each page. This document explains what is the page owner feature and what is the merit of it. And, simple HOW-TO is also explained. See the document for detailed information. Signed-off-by: Joonsoo Kim Cc: Mel Gorman Cc: Johannes Weiner Cc: Minchan Kim Cc: Dave Hansen Cc: Michal Nazarewicz Cc: Jungsoo Son Cc: Ingo Molnar Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Documentation: vm: Add 1GB large page support information

2014-11-06T20:14:11Z

This patch adds 1GB large page support information in Documentation/vm/hugetlbpage.txt Reference: https://lkml.org/lkml/2014/10/31/366 Signed-off-by: Masanari Iida Reviewed-by: Luiz Capitulino Signed-off-by: Jonathan Corbet

Docs: Document that the sticky bit is understood by hugetlbfs

2014-10-22T18:26:04Z

Commit 75897d60 (hugetlb: allow sticky directory mount option) added support for mounting hugetlbfs with sticky option set, like /tmp is usually mounted, but forgot to document that. Acked-by: Ken Chen Signed-off-by: Kirill Smelkov Signed-off-by: Jonathan Corbet

mm: mark remap_file_pages() syscall as deprecated

2014-06-06T23:08:17Z

The remap_file_pages() system call is used to create a nonlinear mapping, that is, a mapping in which the pages of the file are mapped into a nonsequential order in memory. The advantage of using remap_file_pages() over using repeated calls to mmap(2) is that the former approach does not require the kernel to create additional VMA (Virtual Memory Area) data structures. Supporting of nonlinear mapping requires significant amount of non-trivial code in kernel virtual memory subsystem including hot paths. Also to get nonlinear mapping work kernel need a way to distinguish normal page table entries from entries with file offset (pte_file). Kernel reserves flag in PTE for this purpose. PTE flags are scarce resource especially on some CPU architectures. It would be nice to free up the flag for other usage. Fortunately, there are not many users of remap_file_pages() in the wild. It's only known that one enterprise RDBMS implementation uses the syscall on 32-bit systems to map files bigger than can linearly fit into 32-bit virtual address space. This use-case is not critical anymore since 64-bit systems are widely available. The plan is to deprecate the syscall and replace it with an emulation. The emulation will create new VMAs instead of nonlinear mappings. It's going to work slower for rare users of remap_file_pages() but ABI is preserved. One side effect of emulation (apart from performance) is that user can hit vm.max_map_count limit more easily due to additional VMAs. See comment for DEFAULT_MAX_MAP_COUNT for more details on the limit. [akpm@linux-foundation.org: fix spello] Signed-off-by: Kirill A. Shutemov Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Dave Jones Cc: Armin Rigo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory-failure.c: support use of a dedicated thread to handle SIGBUS(BUS_MCEERR_AO)

2014-06-04T23:54:13Z

Currently memory error handler handles action optional errors in the deferred manner by default. And if a recovery aware application wants to handle it immediately, it can do it by setting PF_MCE_EARLY flag. However, such signal can be sent only to the main thread, so it's problematic if the application wants to have a dedicated thread to handler such signals. So this patch adds dedicated thread support to memory error handler. We have PF_MCE_EARLY flags for each thread separately, so with this patch AO signal is sent to the thread with PF_MCE_EARLY flag set, not the main thread. If you want to implement a dedicated thread, you call prctl() to set PF_MCE_EARLY on the thread. Memory error handler collects processes to be killed, so this patch lets it check PF_MCE_EARLY flag on each thread in the collecting routines. No behavioral change for all non-early kill cases. Tony said: : The old behavior was crazy - someone with a multithreaded process might : well expect that if they call prctl(PF_MCE_EARLY) in just one thread, then : that thread would see the SIGBUS with si_code = BUS_MCEERR_A0 - even if : that thread wasn't the main thread for the process. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Naoya Horiguchi Reviewed-by: Tony Luck Cc: Kamil Iskra Cc: Andi Kleen Cc: Borislav Petkov Cc: Chen Gong Cc: [3.2+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds