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2011-07-26ipc: introduce shm_rmid_forced sysctlVasiliy Kulikov
Add support for the shm_rmid_forced sysctl. If set to 1, all shared memory objects in current ipc namespace will be automatically forced to use IPC_RMID. The POSIX way of handling shmem allows one to create shm objects and call shmdt(), leaving shm object associated with no process, thus consuming memory not counted via rlimits. With shm_rmid_forced=1 the shared memory object is counted at least for one process, so OOM killer may effectively kill the fat process holding the shared memory. It obviously breaks POSIX - some programs relying on the feature would stop working. So set shm_rmid_forced=1 only if you're sure nobody uses "orphaned" memory. Use shm_rmid_forced=0 by default for compatability reasons. The feature was previously impemented in -ow as a configure option. [akpm@linux-foundation.org: fix documentation, per Randy] [akpm@linux-foundation.org: fix warning] [akpm@linux-foundation.org: readability/conventionality tweaks] [akpm@linux-foundation.org: fix shm_rmid_forced/shm_forced_rmid confusion, use standard comment layout] Signed-off-by: Vasiliy Kulikov <segoon@openwall.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Serge E. Hallyn" <serge.hallyn@canonical.com> Cc: Daniel Lezcano <daniel.lezcano@free.fr> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Solar Designer <solar@openwall.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-23Documentation: refresh sysctl/kernel.txtBorislav Petkov
Refresh sysctl/kernel.txt. More specifically, - drop stale index entries - sync and sort index and entries - reflow sticking out paragraphs to colwidth 72 - correct typos - cleanup whitespace Signed-off-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-26coredump: add support for exe_file in core nameJiri Slaby
Now, exe_file is not proc FS dependent, so we can use it to name core file. So we add %E pattern for core file name cration which extract path from mm_struct->exe_file. Then it converts slashes to exclamation marks and pastes the result to the core file name itself. This is useful for environments where binary names are longer than 16 character (the current->comm limitation). Also where there are binaries with same name but in a different path. Further in case the binery itself changes its current->comm after exec. So by doing (s/$/#/ -- # is treated as git comment): $ sysctl kernel.core_pattern='core.%p.%e.%E' $ ln /bin/cat cat45678901234567890 $ ./cat45678901234567890 ^Z $ rm cat45678901234567890 $ fg ^\Quit (core dumped) $ ls core* we now get: core.2434.cat456789012345.!root!cat45678901234567890 (deleted) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Reviewed-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-23Documentation: update epoll sysctl textLucian Adrian Grijincu
max_user_instances was removed in this commit: commit 9df04e1f25effde823a600e755b51475d438f56b Author: Davide Libenzi <davidel@xmailserver.org> Date: Thu Jan 29 14:25:26 2009 -0800 epoll: drop max_user_instances and rely only on max_user_watches but the documentation entry was not removed. Cc: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Lucian Adrian Grijincu <lucian.grijincu@gmail.com> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-23Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits) b43: fix comment typo reqest -> request Haavard Skinnemoen has left Atmel cris: typo in mach-fs Makefile Kconfig: fix copy/paste-ism for dell-wmi-aio driver doc: timers-howto: fix a typo ("unsgined") perf: Only include annotate.h once in tools/perf/util/ui/browsers/annotate.c md, raid5: Fix spelling error in comment ('Ofcourse' --> 'Of course'). treewide: fix a few typos in comments regulator: change debug statement be consistent with the style of the rest Revert "arm: mach-u300/gpio: Fix mem_region resource size miscalculations" audit: acquire creds selectively to reduce atomic op overhead rtlwifi: don't touch with treewide double semicolon removal treewide: cleanup continuations and remove logging message whitespace ath9k_hw: don't touch with treewide double semicolon removal include/linux/leds-regulator.h: fix syntax in example code tty: fix typo in descripton of tty_termios_encode_baud_rate xtensa: remove obsolete BKL kernel option from defconfig m68k: fix comment typo 'occcured' arch:Kconfig.locks Remove unused config option. treewide: remove extra semicolons ...
2011-04-27net: filter: Just In Time compiler for x86-64Eric Dumazet
In order to speedup packet filtering, here is an implementation of a JIT compiler for x86_64 It is disabled by default, and must be enabled by the admin. echo 1 >/proc/sys/net/core/bpf_jit_enable It uses module_alloc() and module_free() to get memory in the 2GB text kernel range since we call helpers functions from the generated code. EAX : BPF A accumulator EBX : BPF X accumulator RDI : pointer to skb (first argument given to JIT function) RBP : frame pointer (even if CONFIG_FRAME_POINTER=n) r9d : skb->len - skb->data_len (headlen) r8 : skb->data To get a trace of generated code, use : echo 2 >/proc/sys/net/core/bpf_jit_enable Example of generated code : # tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24 flen=18 proglen=147 pass=3 image=ffffffffa00b5000 JIT code: ffffffffa00b5000: 55 48 89 e5 48 83 ec 60 48 89 5d f8 44 8b 4f 60 JIT code: ffffffffa00b5010: 44 2b 4f 64 4c 8b 87 b8 00 00 00 be 0c 00 00 00 JIT code: ffffffffa00b5020: e8 24 7b f7 e0 3d 00 08 00 00 75 28 be 1a 00 00 JIT code: ffffffffa00b5030: 00 e8 fe 7a f7 e0 24 00 3d 00 14 a8 c0 74 49 be JIT code: ffffffffa00b5040: 1e 00 00 00 e8 eb 7a f7 e0 24 00 3d 00 14 a8 c0 JIT code: ffffffffa00b5050: 74 36 eb 3b 3d 06 08 00 00 74 07 3d 35 80 00 00 JIT code: ffffffffa00b5060: 75 2d be 1c 00 00 00 e8 c8 7a f7 e0 24 00 3d 00 JIT code: ffffffffa00b5070: 14 a8 c0 74 13 be 26 00 00 00 e8 b5 7a f7 e0 24 JIT code: ffffffffa00b5080: 00 3d 00 14 a8 c0 75 07 b8 ff ff 00 00 eb 02 31 JIT code: ffffffffa00b5090: c0 c9 c3 BPF program is 144 bytes long, so native program is almost same size ;) (000) ldh [12] (001) jeq #0x800 jt 2 jf 8 (002) ld [26] (003) and #0xffffff00 (004) jeq #0xc0a81400 jt 16 jf 5 (005) ld [30] (006) and #0xffffff00 (007) jeq #0xc0a81400 jt 16 jf 17 (008) jeq #0x806 jt 10 jf 9 (009) jeq #0x8035 jt 10 jf 17 (010) ld [28] (011) and #0xffffff00 (012) jeq #0xc0a81400 jt 16 jf 13 (013) ld [38] (014) and #0xffffff00 (015) jeq #0xc0a81400 jt 16 jf 17 (016) ret #65535 (017) ret #0 Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Hagen Paul Pfeifer <hagen@jauu.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-04-06doc: fix 3 typos in sysctl/vm.txtPaul Bolle
Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-03-18Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (47 commits) doc: CONFIG_UNEVICTABLE_LRU doesn't exist anymore Update cpuset info & webiste for cgroups dcdbas: force SMI to happen when expected arch/arm/Kconfig: remove one to many l's in the word. asm-generic/user.h: Fix spelling in comment drm: fix printk typo 'sracth' Remove one to many n's in a word Documentation/filesystems/romfs.txt: fixing link to genromfs drivers:scsi Change printk typo initate -> initiate serial, pch uart: Remove duplicate inclusion of linux/pci.h header fs/eventpoll.c: fix spelling mm: Fix out-of-date comments which refers non-existent functions drm: Fix printk typo 'failled' coh901318.c: Change initate to initiate. mbox-db5500.c Change initate to initiate. edac: correct i82975x error-info reported edac: correct i82975x mci initialisation edac: correct commented info fs: update comments to point correct document target: remove duplicate include of target/target_core_device.h from drivers/target/target_core_hba.c ... Trivial conflict in fs/eventpoll.c (spelling vs addition)
2011-03-16Documentation: file handles are now freedFederica Teodori
Since file handles are freed, a little amendment to the documentation Signed-off-by: Federica Teodori <federica.teodori@googlemail.com> Acked-by: Rik van Riel<riel@redhat.com> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-11Documentation: default_message_level is a typoPaul Bolle
It's default_message_loglevel, not default_message_level. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-01-13sysctl: remove obsolete commentsJovi Zhang
ctl_unnumbered.txt have been removed in Documentation directory so just also remove this invalid comments [akpm@linux-foundation.org: fix Documentation/sysctl/00-INDEX, per Dave] Signed-off-by: Jovi Zhang <bookjovi@gmail.com> Cc: Dave Young <hidave.darkstar@gmail.com> Acked-by: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13kptr_restrict for hiding kernel pointers from unprivileged usersDan Rosenberg
Add the %pK printk format specifier and the /proc/sys/kernel/kptr_restrict sysctl. The %pK format specifier is designed to hide exposed kernel pointers, specifically via /proc interfaces. Exposing these pointers provides an easy target for kernel write vulnerabilities, since they reveal the locations of writable structures containing easily triggerable function pointers. The behavior of %pK depends on the kptr_restrict sysctl. If kptr_restrict is set to 0, no deviation from the standard %p behavior occurs. If kptr_restrict is set to 1, the default, if the current user (intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG (currently in the LSM tree), kernel pointers using %pK are printed as 0's. If kptr_restrict is set to 2, kernel pointers using %pK are printed as 0's regardless of privileges. Replacing with 0's was chosen over the default "(null)", which cannot be parsed by userland %p, which expects "(nil)". [akpm@linux-foundation.org: check for IRQ context when !kptr_restrict, save an indent level, s/WARN/WARN_ONCE/] [akpm@linux-foundation.org: coding-style fixup] [randy.dunlap@oracle.com: fix kernel/sysctl.c warning] Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: James Morris <jmorris@namei.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Thomas Graf <tgraf@infradead.org> Cc: Eugene Teo <eugeneteo@kernel.org> Cc: Kees Cook <kees.cook@canonical.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David S. Miller <davem@davemloft.net> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Paris <eparis@parisplace.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-12-09syslog: check cap_syslog when dmesg_restrictSerge E. Hallyn
Eric Paris pointed out that it doesn't make sense to require both CAP_SYS_ADMIN and CAP_SYSLOG for certain syslog actions. So require CAP_SYSLOG, not CAP_SYS_ADMIN, when dmesg_restrict is set. (I'm also consolidating the now common error path) Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: Eric Paris <eparis@redhat.com> Acked-by: Kees Cook <kees.cook@canonical.com> Signed-off-by: James Morris <jmorris@namei.org>
2010-11-12Restrict unprivileged access to kernel syslogDan Rosenberg
The kernel syslog contains debugging information that is often useful during exploitation of other vulnerabilities, such as kernel heap addresses. Rather than futilely attempt to sanitize hundreds (or thousands) of printk statements and simultaneously cripple useful debugging functionality, it is far simpler to create an option that prevents unprivileged users from reading the syslog. This patch, loosely based on grsecurity's GRKERNSEC_DMESG, creates the dmesg_restrict sysctl. When set to "0", the default, no restrictions are enforced. When set to "1", only users with CAP_SYS_ADMIN can read the kernel syslog via dmesg(8) or other mechanisms. [akpm@linux-foundation.org: explain the config option in kernel.txt] Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Eugene Teo <eugeneteo@kernel.org> Acked-by: Kees Cook <kees.cook@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-27doc: clarify the behaviour of dirty_ratio/dirty_bytesAndrea Righi
When dirty_ratio or dirty_bytes is written the other parameter is disabled and set to 0 (in dirty_bytes_handler() / dirty_ratio_handler()). We do the same for dirty_background_ratio and dirty_background_bytes. However, in the sysctl documentation, we say that the counterpart becomes a function of the old value, that is not correct. Clarify the documentation reporting the actual behaviour. Reviewed-by: Greg Thelen <gthelen@google.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrea Righi <arighi@develer.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-09oom: enable oom tasklist dump by defaultDavid Rientjes
The oom killer tasklist dump, enabled with the oom_dump_tasks sysctl, is very helpful information in diagnosing why a user's task has been killed. It emits useful information such as each eligible thread's memory usage that can determine why the system is oom, so it should be enabled by default. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: 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>
2010-06-28Documentation/sysctl/vm.txt typoKulikov Vasiliy
Fix trivial typo: duplicated word. Signed-off-by: Kulikov Vasiliy <segooon@gmail.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-05-25mm: compaction: add a tunable that decides when memory should be compacted ↵Mel Gorman
and when it should be reclaimed The kernel applies some heuristics when deciding if memory should be compacted or reclaimed to satisfy a high-order allocation. One of these is based on the fragmentation. If the index is below 500, memory will not be compacted. This choice is arbitrary and not based on data. To help optimise the system and set a sensible default for this value, this patch adds a sysctl extfrag_threshold. The kernel will only compact memory if the fragmentation index is above the extfrag_threshold. [randy.dunlap@oracle.com: Fix build errors when proc fs is not configured] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: 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>
2010-05-25mm: compaction: add /proc trigger for memory compactionMel Gorman
Add a proc file /proc/sys/vm/compact_memory. When an arbitrary value is written to the file, all zones are compacted. The expected user of such a trigger is a job scheduler that prepares the system before the target application runs. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-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>
2010-05-15net: Consistent skb timestampingEric Dumazet
With RPS inclusion, skb timestamping is not consistent in RX path. If netif_receive_skb() is used, its deferred after RPS dispatch. If netif_rx() is used, its done before RPS dispatch. This can give strange tcpdump timestamps results. I think timestamping should be done as soon as possible in the receive path, to get meaningful values (ie timestamps taken at the time packet was delivered by NIC driver to our stack), even if NAPI already can defer timestamping a bit (RPS can help to reduce the gap) Tom Herbert prefer to sample timestamps after RPS dispatch. In case sampling is expensive (HPET/acpi_pm on x86), this makes sense. Let admins switch from one mode to another, using a new sysctl, /proc/sys/net/core/netdev_tstamp_prequeue Its default value (1), means timestamps are taken as soon as possible, before backlog queueing, giving accurate timestamps. Setting a 0 value permits to sample timestamps when processing backlog, after RPS dispatch, to lower the load of the pre-RPS cpu. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-03-12memcg: handle panic_on_oom=always caseKAMEZAWA Hiroyuki
Presently, if panic_on_oom=2, the whole system panics even if the oom happend in some special situation (as cpuset, mempolicy....). Then, panic_on_oom=2 means painc_on_oom_always. Now, memcg doesn't check panic_on_oom flag. This patch adds a check. BTW, how it's useful ? kdump+panic_on_oom=2 is the last tool to investigate what happens in oom-ed system. When a task is killed, the sysytem recovers and there will be few hint to know what happnes. In mission critical system, oom should never happen. Then, panic_on_oom=2+kdump is useful to avoid next OOM by knowing precise information via snapshot. TODO: - For memcg, it's for isolate system's memory usage, oom-notiifer and freeze_at_oom (or rest_at_oom) should be implemented. Then, management daemon can do similar jobs (as kdump) or taking snapshot per cgroup. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Nick Piggin <npiggin@suse.de> Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-11doc: Add documentation for bootloader_{type,version}H. Peter Anvin
Add documentation for kernel/bootloader_type and kernel/bootloader_version to sysctl/kernel.txt. This should really have been done a long time ago. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Shen Feng <shen@cn.fujitsu.com>
2009-12-09Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (42 commits) tree-wide: fix misspelling of "definition" in comments reiserfs: fix misspelling of "journaled" doc: Fix a typo in slub.txt. inotify: remove superfluous return code check hdlc: spelling fix in find_pvc() comment doc: fix regulator docs cut-and-pasteism mtd: Fix comment in Kconfig doc: Fix IRQ chip docs tree-wide: fix assorted typos all over the place drivers/ata/libata-sff.c: comment spelling fixes fix typos/grammos in Documentation/edac.txt sysctl: add missing comments fs/debugfs/inode.c: fix comment typos sgivwfb: Make use of ARRAY_SIZE. sky2: fix sky2_link_down copy/paste comment error tree-wide: fix typos "couter" -> "counter" tree-wide: fix typos "offest" -> "offset" fix kerneldoc for set_irq_msi() spidev: fix double "of of" in comment comment typo fix: sybsystem -> subsystem ...
2009-12-04tree-wide: fix assorted typos all over the placeAndré Goddard Rosa
That is "success", "unknown", "through", "performance", "[re|un]mapping" , "access", "default", "reasonable", "[con]currently", "temperature" , "channel", "[un]used", "application", "example","hierarchy", "therefore" , "[over|under]flow", "contiguous", "threshold", "enough" and others. Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-11-18sysctl: Remove CTL_NONE and CTL_UNNUMBEREDEric W. Biederman
Now that the sysctl structures no longer have a ctl_name field there is no reason to retain the definitions for CTL_NONE and CTL_UNNUMBERED, or to explain their historic usage. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2009-11-09docs: fix core_pipe_limit infoRandy Dunlap
Fix typos in core_pipe_limit info. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-09-24Merge branch 'hwpoison' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 * 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: (21 commits) HWPOISON: Enable error_remove_page on btrfs HWPOISON: Add simple debugfs interface to inject hwpoison on arbitary PFNs HWPOISON: Add madvise() based injector for hardware poisoned pages v4 HWPOISON: Enable error_remove_page for NFS HWPOISON: Enable .remove_error_page for migration aware file systems HWPOISON: The high level memory error handler in the VM v7 HWPOISON: Add PR_MCE_KILL prctl to control early kill behaviour per process HWPOISON: shmem: call set_page_dirty() with locked page HWPOISON: Define a new error_remove_page address space op for async truncation HWPOISON: Add invalidate_inode_page HWPOISON: Refactor truncate to allow direct truncating of page v2 HWPOISON: check and isolate corrupted free pages v2 HWPOISON: Handle hardware poisoned pages in try_to_unmap HWPOISON: Use bitmask/action code for try_to_unmap behaviour HWPOISON: x86: Add VM_FAULT_HWPOISON handling to x86 page fault handler v2 HWPOISON: Add poison check to page fault handling HWPOISON: Add basic support for poisoned pages in fault handler v3 HWPOISON: Add new SIGBUS error codes for hardware poison signals HWPOISON: Add support for poison swap entries v2 HWPOISON: Export some rmap vma locking to outside world ...
2009-09-24exec: let do_coredump() limit the number of concurrent dumps to pipesNeil Horman
Introduce core pipe limiting sysctl. Since we can dump cores to pipe, rather than directly to the filesystem, we create a condition in which a user can create a very high load on the system simply by running bad applications. If the pipe reader specified in core_pattern is poorly written, we can have lots of ourstandig resources and processes in the system. This sysctl introduces an ability to limit that resource consumption. core_pipe_limit defines how many in-flight dumps may be run in parallel, dumps beyond this value are skipped and a note is made in the kernel log. A special value of 0 in core_pipe_limit denotes unlimited core dumps may be handled (this is the default value). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Reported-by: Earl Chew <earl_chew@agilent.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Andi Kleen <andi@firstfloor.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-24Documentation: update stale definition of file-nr in fs.txtXiaotian Feng
In "documentation: update Documentation/filesystem/proc.txt and Documentation/sysctls" (commit 760df93ec) we merged /proc/sys/fs documentation in Documentation/sysctl/fs.txt and Documentation/filesystem/proc.txt, but stale file-nr definition remained. This patch adds back the right fs-nr definition for 2.6 kernel. Signed-off-by: Xiaotian Feng<dfeng@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-23printk: add printk_delay to make messages readable for some scenariosDave Young
When syslog is not possible, at the same time there's no serial/net console available, it will be hard to read the printk messages. For example oops/panic/warning messages in shutdown phase. Add a printk delay feature, we can make each printk message delay some milliseconds. Setting the delay by proc/sysctl interface: /proc/sys/kernel/printk_delay The value range from 0 - 10000, default value is 0 [akpm@linux-foundation.org: fix a few things] Signed-off-by: Dave Young <hidave.darkstar@gmail.com> 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>
2009-09-22Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits) trivial: fix typo in aic7xxx comment trivial: fix comment typo in drivers/ata/pata_hpt37x.c trivial: typo in kernel-parameters.txt trivial: fix typo in tracing documentation trivial: add __init/__exit macros in drivers/gpio/bt8xxgpio.c trivial: add __init macro/ fix of __exit macro location in ipmi_poweroff.c trivial: remove unnecessary semicolons trivial: Fix duplicated word "options" in comment trivial: kbuild: remove extraneous blank line after declaration of usage() trivial: improve help text for mm debug config options trivial: doc: hpfall: accept disk device to unload as argument trivial: doc: hpfall: reduce risk that hpfall can do harm trivial: SubmittingPatches: Fix reference to renumbered step trivial: fix typos "man[ae]g?ment" -> "management" trivial: media/video/cx88: add __init/__exit macros to cx88 drivers trivial: fix typo in CONFIG_DEBUG_FS in gcov doc trivial: fix missing printk space in amd_k7_smp_check trivial: fix typo s/ketymap/keymap/ in comment trivial: fix typo "to to" in multiple files trivial: fix typos in comments s/DGBU/DBGU/ ...
2009-09-22vm: document that setting vfs_cache_pressure to 0 isn't a good ideaJan Kara
Reported-by: Christian Thaeter <ct@pipapo.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-21trivial: doc: document missing value 2 for randomize-va-spaceHorst Schirmeier
The documentation for /proc/sys/kernel/* does not mention the possible value 2 for randomize-va-space yet. While being there, doing some reformatting, fixing grammar problems and clarifying the correlations between randomize-va-space, kernel parameter "norandmaps" and the CONFIG_COMPAT_BRK option. Signed-off-by: Horst Schirmeier <horst@schirmeier.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-09-16HWPOISON: The high level memory error handler in the VM v7Andi Kleen
Add the high level memory handler that poisons pages that got corrupted by hardware (typically by a two bit flip in a DIMM or a cache) on the Linux level. The goal is to prevent everyone from accessing these pages in the future. This done at the VM level by marking a page hwpoisoned and doing the appropriate action based on the type of page it is. The code that does this is portable and lives in mm/memory-failure.c To quote the overview comment: High level machine check handler. Handles pages reported by the hardware as being corrupted usually due to a 2bit ECC memory or cache failure. This focuses on pages detected as corrupted in the background. When the current CPU tries to consume corruption the currently running process can just be killed directly instead. This implies that if the error cannot be handled for some reason it's safe to just ignore it because no corruption has been consumed yet. Instead when that happens another machine check will happen. Handles page cache pages in various states. The tricky part here is that we can access any page asynchronous to other VM users, because memory failures could happen anytime and anywhere, possibly violating some of their assumptions. This is why this code has to be extremely careful. Generally it tries to use normal locking rules, as in get the standard locks, even if that means the error handling takes potentially a long time. Some of the operations here are somewhat inefficient and have non linear algorithmic complexity, because the data structures have not been optimized for this case. This is in particular the case for the mapping from a vma to a process. Since this case is expected to be rare we hope we can get away with this. There are in principle two strategies to kill processes on poison: - just unmap the data and wait for an actual reference before killing - kill as soon as corruption is detected. Both have advantages and disadvantages and should be used in different situations. Right now both are implemented and can be switched with a new sysctl vm.memory_failure_early_kill The default is early kill. The patch does some rmap data structure walking on its own to collect processes to kill. This is unusual because normally all rmap data structure knowledge is in rmap.c only. I put it here for now to keep everything together and rmap knowledge has been seeping out anyways Includes contributions from Johannes Weiner, Chris Mason, Fengguang Wu, Nick Piggin (who did a lot of great work) and others. Cc: npiggin@suse.de Cc: riel@redhat.com Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
2009-09-11[S390] add call home supportHans-Joachim Picht
Signed-off-by: Hans-Joachim Picht <hans@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-06-16vmscan: properly account for the number of page cache pages zone_reclaim() ↵Mel Gorman
can reclaim A bug was brought to my attention against a distro kernel but it affects mainline and I believe problems like this have been reported in various guises on the mailing lists although I don't have specific examples at the moment. The reported problem was that malloc() stalled for a long time (minutes in some cases) if a large tmpfs mount was occupying a large percentage of memory overall. The pages did not get cleaned or reclaimed by zone_reclaim() because the zone_reclaim_mode was unsuitable, but the lists are uselessly scanned frequencly making the CPU spin at near 100%. This patchset intends to address that bug and bring the behaviour of zone_reclaim() more in line with expectations which were noticed during investigation. It is based on top of mmotm and takes advantage of Kosaki's work with respect to zone_reclaim(). Patch 1 fixes the heuristics that zone_reclaim() uses to determine if the scan should go ahead. The broken heuristic is what was causing the malloc() stall as it uselessly scanned the LRU constantly. Currently, zone_reclaim is assuming zone_reclaim_mode is 1 and historically it could not deal with tmpfs pages at all. This fixes up the heuristic so that an unnecessary scan is more likely to be correctly avoided. Patch 2 notes that zone_reclaim() returning a failure automatically means the zone is marked full. This is not always true. It could have failed because the GFP mask or zone_reclaim_mode were unsuitable. Patch 3 introduces a counter zreclaim_failed that will increment each time the zone_reclaim scan-avoidance heuristics fail. If that counter is rapidly increasing, then zone_reclaim_mode should be set to 0 as a temporarily resolution and a bug reported because the scan-avoidance heuristic is still broken. This patch: On NUMA machines, the administrator can configure zone_reclaim_mode that is a more targetted form of direct reclaim. On machines with large NUMA distances for example, a zone_reclaim_mode defaults to 1 meaning that clean unmapped pages will be reclaimed if the zone watermarks are not being met. There is a heuristic that determines if the scan is worthwhile but the problem is that the heuristic is not being properly applied and is basically assuming zone_reclaim_mode is 1 if it is enabled. The lack of proper detection can manfiest as high CPU usage as the LRU list is scanned uselessly. Historically, once enabled it was depending on NR_FILE_PAGES which may include swapcache pages that the reclaim_mode cannot deal with. Patch vmscan-change-the-number-of-the-unmapped-files-in-zone-reclaim.patch by Kosaki Motohiro noted that zone_page_state(zone, NR_FILE_PAGES) included pages that were not file-backed such as swapcache and made a calculation based on the inactive, active and mapped files. This is far superior when zone_reclaim==1 but if RECLAIM_SWAP is set, then NR_FILE_PAGES is a reasonable starting figure. This patch alters how zone_reclaim() works out how many pages it might be able to reclaim given the current reclaim_mode. If RECLAIM_SWAP is set in the reclaim_mode it will either consider NR_FILE_PAGES as potential candidates or else use NR_{IN}ACTIVE}_PAGES-NR_FILE_MAPPED to discount swapcache and other non-file-backed pages. If RECLAIM_WRITE is not set, then NR_FILE_DIRTY number of pages are not candidates. If RECLAIM_SWAP is not set, then NR_FILE_MAPPED are not. [kosaki.motohiro@jp.fujitsu.com: Estimate unmapped pages minus tmpfs pages] [fengguang.wu@intel.com: Fix underflow problem in Kosaki's estimate] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Christoph Lameter <cl@linux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16page allocator: use allocation flags as an index to the zone watermarkMel Gorman
ALLOC_WMARK_MIN, ALLOC_WMARK_LOW and ALLOC_WMARK_HIGH determin whether pages_min, pages_low or pages_high is used as the zone watermark when allocating the pages. Two branches in the allocator hotpath determine which watermark to use. This patch uses the flags as an array index into a watermark array that is indexed with WMARK_* defines accessed via helpers. All call sites that use zone->pages_* are updated to use the helpers for accessing the values and the array offsets for setting. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-12trivial: Miscellaneous documentation typo fixesMatt LaPlante
Fix various typos in documentation txts. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-05-22Merge branch 'master' into nextJames Morris
Conflicts: fs/exec.c Removed IMA changes (the IMA checks are now performed via may_open()). Signed-off-by: James Morris <jmorris@namei.org>
2009-05-15Revert "mm: add /proc controls for pdflush threads"Jens Axboe
This reverts commit fafd688e4c0c34da0f3de909881117d374e4c7af. Work is progressing to switch away from pdflush as the process backing for flushing out dirty data. So it seems pointless to add more knobs to control pdflush threads. The original author of the patch did not have any specific use cases for adding the knobs, so we can easily revert this before 2.6.30 to avoid having to maintain this API forever. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-08Merge branch 'master' into nextJames Morris
2009-05-02mm: prevent divide error for small values of vm_dirty_bytesAndrea Righi
Avoid setting less than two pages for vm_dirty_bytes: this is necessary to avoid potential division by 0 (like the following) in get_dirty_limits(). [ 49.951610] divide error: 0000 [#1] PREEMPT SMP [ 49.952195] last sysfs file: /sys/devices/pci0000:00/0000:00:01.1/host0/target0:0:0/0:0:0:0/block/sda/uevent [ 49.952195] CPU 1 [ 49.952195] Modules linked in: pcspkr [ 49.952195] Pid: 3064, comm: dd Not tainted 2.6.30-rc3 #1 [ 49.952195] RIP: 0010:[<ffffffff802d39a9>] [<ffffffff802d39a9>] get_dirty_limits+0xe9/0x2c0 [ 49.952195] RSP: 0018:ffff88001de03a98 EFLAGS: 00010202 [ 49.952195] RAX: 00000000000000c0 RBX: ffff88001de03b80 RCX: 28f5c28f5c28f5c3 [ 49.952195] RDX: 0000000000000000 RSI: 00000000000000c0 RDI: 0000000000000000 [ 49.952195] RBP: ffff88001de03ae8 R08: 0000000000000000 R09: 0000000000000000 [ 49.952195] R10: ffff88001ddda9a0 R11: 0000000000000001 R12: 0000000000000001 [ 49.952195] R13: ffff88001fbc8218 R14: ffff88001de03b70 R15: ffff88001de03b78 [ 49.952195] FS: 00007fe9a435b6f0(0000) GS:ffff8800025d9000(0000) knlGS:0000000000000000 [ 49.952195] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 49.952195] CR2: 00007fe9a39ab000 CR3: 000000001de38000 CR4: 00000000000006e0 [ 49.952195] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 49.952195] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 49.952195] Process dd (pid: 3064, threadinfo ffff88001de02000, task ffff88001ddda250) [ 49.952195] Stack: [ 49.952195] ffff88001fa0de00 ffff88001f2dbd70 ffff88001f9fe800 000080b900000000 [ 49.952195] 00000000000000c0 ffff8800027a6100 0000000000000400 ffff88001fbc8218 [ 49.952195] 0000000000000000 0000000000000600 ffff88001de03bb8 ffffffff802d3ed7 [ 49.952195] Call Trace: [ 49.952195] [<ffffffff802d3ed7>] balance_dirty_pages_ratelimited_nr+0x1d7/0x3f0 [ 49.952195] [<ffffffff80368f8e>] ? ext3_writeback_write_end+0x9e/0x120 [ 49.952195] [<ffffffff802cc7df>] generic_file_buffered_write+0x12f/0x330 [ 49.952195] [<ffffffff802cce8d>] __generic_file_aio_write_nolock+0x26d/0x460 [ 49.952195] [<ffffffff802cda32>] ? generic_file_aio_write+0x52/0xd0 [ 49.952195] [<ffffffff802cda49>] generic_file_aio_write+0x69/0xd0 [ 49.952195] [<ffffffff80365fa6>] ext3_file_write+0x26/0xc0 [ 49.952195] [<ffffffff803034d1>] do_sync_write+0xf1/0x140 [ 49.952195] [<ffffffff80290d1a>] ? get_lock_stats+0x2a/0x60 [ 49.952195] [<ffffffff80280730>] ? autoremove_wake_function+0x0/0x40 [ 49.952195] [<ffffffff8030411b>] vfs_write+0xcb/0x190 [ 49.952195] [<ffffffff803042d0>] sys_write+0x50/0x90 [ 49.952195] [<ffffffff8022ff6b>] system_call_fastpath+0x16/0x1b [ 49.952195] Code: 00 00 00 2b 05 09 1c 17 01 48 89 c6 49 0f af f4 48 c1 ee 02 48 89 f0 48 f7 e1 48 89 d6 31 d2 48 c1 ee 02 48 0f af 75 d0 48 89 f0 <48> f7 f7 41 8b 95 ac 01 00 00 48 89 c7 49 0f af d4 48 c1 ea 02 [ 49.952195] RIP [<ffffffff802d39a9>] get_dirty_limits+0xe9/0x2c0 [ 49.952195] RSP <ffff88001de03a98> [ 50.096523] ---[ end trace 008d7aa02f244d7b ]--- Signed-off-by: Andrea Righi <righi.andrea@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Rientjes <rientjes@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-13Documentation/sysctl/net.txt: fix a typoLi Zefan
s/spicified/specified Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-07mm: add /proc controls for pdflush threadsPeter W Morreale
Add /proc entries to give the admin the ability to control the minimum and maximum number of pdflush threads. This allows finer control of pdflush on both large and small machines. The rationale is simply one size does not fit all. Admins on large and/or small systems may want to tune the min/max pdflush thread count to best suit their needs. Right now the min/max is hardcoded to 2/8. While probably a fair estimate for smaller machines, large machines with large numbers of CPUs and large numbers of filesystems/block devices may benefit from larger numbers of threads working on different block devices. Even if the background flushing algorithm is radically changed, it is still likely that multiple threads will be involved and admins would still desire finer control on the min/max other than to have to recompile the kernel. The patch adds '/proc/sys/vm/nr_pdflush_threads_min' and '/proc/sys/vm/nr_pdflush_threads_max' with r/w permissions. The minimum value for nr_pdflush_threads_min is 1 and the maximum value is the current value of nr_pdflush_threads_max. This minimum is required since additional thread creation is performed in a pdflush thread itself. The minimum value for nr_pdflush_threads_max is the current value of nr_pdflush_threads_min and the maximum value can be 1000. Documentation/sysctl/vm.txt is also updated. [akpm@linux-foundation.org: fix comment, fix whitespace, use __read_mostly] Signed-off-by: Peter W Morreale <pmorreale@novell.com> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02documentation: fix unix_dgram_qlen descriptionLi Xiaodong
Previous description about system parameter in /proc/sys/net/unix/ is wrong (or missed). Simply add a new description about unix_dgram_qlen according to latest kernel. Signed-off-by: Li Xiaodong <lixd@cn.fujitsu.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02documentation: update Documentation/filesystem/proc.txt and ↵Shen Feng
Documentation/sysctls Now /proc/sys is described in many places and much information is redundant. This patch updates the proc.txt and move the /proc/sys desciption out to the files in Documentation/sysctls. Details are: merge - 2.1 /proc/sys/fs - File system data - 2.11 /proc/sys/fs/mqueue - POSIX message queues filesystem - 2.17 /proc/sys/fs/epoll - Configuration options for the epoll interface with Documentation/sysctls/fs.txt. remove - 2.2 /proc/sys/fs/binfmt_misc - Miscellaneous binary formats since it's not better then the Documentation/binfmt_misc.txt. merge - 2.3 /proc/sys/kernel - general kernel parameters with Documentation/sysctls/kernel.txt remove - 2.5 /proc/sys/dev - Device specific parameters since it's obsolete the sysfs is used now. remove - 2.6 /proc/sys/sunrpc - Remote procedure calls since it's not better then the Documentation/sysctls/sunrpc.txt move - 2.7 /proc/sys/net - Networking stuff - 2.9 Appletalk - 2.10 IPX to newly created Documentation/sysctls/net.txt. remove - 2.8 /proc/sys/net/ipv4 - IPV4 settings since it's not better then the Documentation/networking/ip-sysctl.txt. add - Chapter 3 Per-Process Parameters to descibe /proc/<pid>/xxx parameters. Signed-off-by: Shen Feng <shen@cn.fujitsu.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-03modules: sysctl to block module loadingKees Cook
Implement a sysctl file that disables module-loading system-wide since there is no longer a viable way to remove CAP_SYS_MODULE after the system bounding capability set was removed in 2.6.25. Value can only be set to "1", and is tested only if standard capability checks allow CAP_SYS_MODULE. Given existing /dev/mem protections, this should allow administrators a one-way method to block module loading after initial boot-time module loading has finished. Signed-off-by: Kees Cook <kees.cook@canonical.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-01-15Update of Documentation: vm.txt and proc.txtPeter W Morreale
Update Documentation/sysctl/vm.txt and Documentation/filesystems/proc.txt. More specifically, the section on /proc/sys/vm in Documentation/filesystems/proc.txt was removed and a link to Documentation/sysctl/vm.txt added. Most of the verbiage from proc.txt was simply moved in vm.txt, with new addtional text for "swappiness" and "stat_interval". Signed-off-by: Peter W Morreale <pmorreale@novell.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-08NOMMU: Make mmap allocation page trimming behaviour configurable.Paul Mundt
NOMMU mmap allocates a piece of memory for an mmap that's rounded up in size to the nearest power-of-2 number of pages. Currently it then discards the excess pages back to the page allocator, making that memory available for use by other things. This can, however, cause greater amount of fragmentation. To counter this, a sysctl is added in order to fine-tune the trimming behaviour. The default behaviour remains to trim pages aggressively, while this can either be disabled completely or set to a higher page-granular watermark in order to have finer-grained control. vm region vm_top bits taken from an earlier patch by David Howells. Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Mike Frysinger <vapier.adi@gmail.com>
2009-01-06mm: add dirty_background_bytes and dirty_bytes sysctlsDavid Rientjes
This change introduces two new sysctls to /proc/sys/vm: dirty_background_bytes and dirty_bytes. dirty_background_bytes is the counterpart to dirty_background_ratio and dirty_bytes is the counterpart to dirty_ratio. With growing memory capacities of individual machines, it's no longer sufficient to specify dirty thresholds as a percentage of the amount of dirtyable memory over the entire system. dirty_background_bytes and dirty_bytes specify quantities of memory, in bytes, that represent the dirty limits for the entire system. If either of these values is set, its value represents the amount of dirty memory that is needed to commence either background or direct writeback. When a `bytes' or `ratio' file is written, its counterpart becomes a function of the written value. For example, if dirty_bytes is written to be 8096, 8K of memory is required to commence direct writeback. dirty_ratio is then functionally equivalent to 8K / the amount of dirtyable memory: dirtyable_memory = free pages + mapped pages + file cache dirty_background_bytes = dirty_background_ratio * dirtyable_memory -or- dirty_background_ratio = dirty_background_bytes / dirtyable_memory AND dirty_bytes = dirty_ratio * dirtyable_memory -or- dirty_ratio = dirty_bytes / dirtyable_memory Only one of dirty_background_bytes and dirty_background_ratio may be specified at a time, and only one of dirty_bytes and dirty_ratio may be specified. When one sysctl is written, the other appears as 0 when read. The `bytes' files operate on a page size granularity since dirty limits are compared with ZVC values, which are in page units. Prior to this change, the minimum dirty_ratio was 5 as implemented by get_dirty_limits() although /proc/sys/vm/dirty_ratio would show any user written value between 0 and 100. This restriction is maintained, but dirty_bytes has a lower limit of only one page. Also prior to this change, the dirty_background_ratio could not equal or exceed dirty_ratio. This restriction is maintained in addition to restricting dirty_background_bytes. If either background threshold equals or exceeds that of the dirty threshold, it is implicitly set to half the dirty threshold. Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Cc: Andrea Righi <righi.andrea@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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