- 17 Jun, 2009 40 commits
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Joe Perches authored
Signed-off-by:
Joe Perches <joe@perches.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Joe Perches authored
Fix mailing lists that are described, but not "(subscriber-only)" Signed-off-by:
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Zygo Blaxell authored
There is a call to write_lock() in gen_pool_destroy which is not balanced by any corresponding write_unlock(). This causes problems with preemption because the preemption-disable counter is incremented in the write_lock() call, but never decremented by any call to write_unlock(). This bug is gen_pool_destroy, and one of them is non-x86 arch-specific code. Signed-off-by:
Zygo Blaxell <zygo.blaxell@xandros.com> Cc: Jiri Kosina <trivial@kernel.org> Cc: Steve Wise <swise@opengridcomputing.com> Cc: <stable@kernel.org> Signed-off-by:
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Tomas Szepe authored
CONFIG_FILE_LOCKING should not depend on CONFIG_BLOCK. This makes it possible to run complete systems out of a CONFIG_BLOCK=n initramfs on current kernels again (this last worked on 2.6.27.*). Cc: <stable@kernel.org> Signed-off-by:
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Florian Fainelli authored
Add support for the TI VLYNQ high-speed, serial and packetized bus. This bus allows external devices to be connected to the System-on-Chip and appear in the main system memory just like any memory mapped peripheral. It is widely used in TI's networking and multimedia SoC, including the AR7 SoC. Signed-off-by:
Eugene Konev <ejka@imfi.kspu.ru> Signed-off-by:
Florian Fainelli <florian@openwrt.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg KH <greg@kroah.com> Signed-off-by:
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Daniel Mack authored
The console blank timer is currently hardcoded to 10*60 seconds which might be annoying on systems with no input devices attached to wake up the console again. Especially during development, disabling the screen saver can be handy - for example when debugging the root fs mount mechanism or other scenarios where no userspace program could be started to do that at runtime from userspace. This patch defines a core_param for the variable in charge which allows users to entirely disable the blank feature at boot time by setting it 0. The value can still be overwritten at runtime using the standard ioctl call - this just allows to conditionally change the default. Signed-off-by:
Daniel Mack <daniel@caiaq.de> Signed-off-by:
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Figo.zhang authored
list_add() lost a parameter in sample code. Signed-off-by:
Figo.zhang <figo1802@gmail.com> Signed-off-by:
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Maciej W. Rozycki authored
Add EISA IDs for Network Peripherals FDDI boards. Descriptions taken from the respective EISA configuration files. It's unlikely we'll ever support these cards, the problem being the lack of documentation. Assuming the policy for the EISA ID database is the same as for PCI I'm sending these entries for the sake of completeness. Signed-off-by:
Maciej W. Rozycki <macro@linux-mips.org> Cc: Marc Zyngier <maz@misterjones.org> Signed-off-by:
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Masatake YAMATO authored
sys_pipe2 is declared twice in include/linux/syscalls.h. Signed-off-by:
Masatake YAMATO <yamato@redhat.com> Signed-off-by:
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Randy Dunlap authored
Convert most arches to use asm-generic/kmap_types.h. Move the KM_FENCE_ macro additions into asm-generic/kmap_types.h, controlled by __WITH_KM_FENCE from each arch's kmap_types.h file. Would be nice to be able to add custom KM_types per arch, but I don't yet see a nice, clean way to do that. Built on x86_64, i386, mips, sparc, alpha(tonyb), powerpc(tonyb), and 68k(tonyb). Note: avr32 should be able to remove KM_PTE2 (since it's not used) and then just use the generic kmap_types.h file. Get avr32 maintainer approval. Signed-off-by:
Randy Dunlap <randy.dunlap@oracle.com> Cc: <linux-arch@vger.kernel.org> Acked-by:
Mike Frysinger <vapier@gentoo.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Bryan Wu <cooloney@kernel.org> Cc: Mikael Starvik <starvik@axis.com> Cc: Hirokazu Takata <takata@linux-m32r.org> Cc: "Luck Tony" <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: David Howells <dhowells@redhat.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:
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Jaswinder Singh Rajput authored
Fix compilation warning: Documentation/accounting/getdelays.c: In function `main': Documentation/accounting/getdelays.c:249: warning: `cmd_type' may be used uninitialized in this function This is in fact a false positive. Signed-off-by:
Jaswinder Singh Rajput <jaswinderrajput@gmail.com> Acked-by:
Balbir Singh <balbir@in.ibm.com> Signed-off-by:
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Li Zefan authored
For example: hex_dump_to_buffer("AB", 2, 16, 1, buf, 100, 0); pr_info("[%s]\n", buf); I'd expect the output to be "[41 42]", but actually it's "[41 42 ]" This patch also makes the required buf to be minimum. To print the hex format of "AB", a buf with size 6 should be sufficient, but hex_dump_to_buffer() required at least 8. Signed-off-by:Li Zefan <lizf@cn.fujitsu.com> Acked-by:
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Minchan Kim authored
There are some places to be able to use printk_once instead of hard coding. Signed-off-by:
Minchan Kim <minchan.kim@gmail.com> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: David S. Miller <davem@davemloft.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by:
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Chris Peterson authored
Round the slow work queue's cull and OOM timeouts to whole second boundary with round_jiffies(). The slow work queue uses a pair of timers to cull idle threads and, after OOM, to delay new thread creation. This patch also extracts the mod_timer() logic for the cull timer into a separate helper function. By rounding non-time-critical timers such as these to whole seconds, they will be batched up to fire at the same time rather than being spread out. This allows the CPU wake up less, which saves power. Signed-off-by:
Chris Peterson <cpeterso@cpeterso.com> Signed-off-by:
David Howells <dhowells@redhat.com> Signed-off-by:
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Huang Shijie authored
radix_tree_lookup() and radix_tree_lookup_slot() have much the same code except for the return value. Introduce radix_tree_lookup_element() to do the real work. /* * is_slot == 1 : search for the slot. * is_slot == 0 : search for the node. */ static void * radix_tree_lookup_element(struct radix_tree_root *root, unsigned long index, int is_slot); Signed-off-by:
Huang Shijie <shijie8@gmail.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by:
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Alexey Dobriyan authored
Move supplementary groups implementation to kernel/groups.c . kernel/sys.c already accumulated quite a few random stuff. Do strictly copy/paste + add required headers to compile. Compile-tested on many configs and archs. Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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Thomas Gleixner authored
put_cpu_no_resched() is an optimization of put_cpu() which unfortunately can cause high latencies. The nfs iostats code uses put_cpu_no_resched() in a code sequence where a reschedule request caused by an interrupt between the get_cpu() and the put_cpu_no_resched() can delay the reschedule for at least HZ. The other users of put_cpu_no_resched() optimize correctly in interrupt code, but there is no real harm in using the put_cpu() function which is an alias for preempt_enable(). The extra check of the preemmpt count is not as critical as the potential source of missing a reschedule. Debugged in the preempt-rt tree and verified in mainline. Impact: remove a high latency source [akpm@linux-foundation.org: build fix] Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Acked-by:
Ingo Molnar <mingo@elte.hu> Cc: Tony Luck <tony.luck@intel.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by:
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Philipp Reisner authored
Since we have had a LANANA major number for years, and it is documented in devices.txt, I think that this first patch can go upstream. Signed-off-by:
Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by:
Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by:
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Andrew Morton authored
They're in linux/bug.h at present, which causes include order tangles. In particular, linux/bug.h cannot be used by linux/atomic.h because, according to Nikanth: linux/bug.h pulls in linux/module.h => linux/spinlock.h => asm/spinlock.h (which uses atomic_inc) => asm/atomic.h. bug.h is a pretty low-level thing and module.h is a higher-level thing, IMO. Cc: Nikanth Karthikesan <knikanth@novell.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:
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Eric Dumazet authored
After introduction of keyed wakeups Davide Libenzi did on epoll, we are able to avoid spurious wakeups in poll()/select() code too. For example, typical use of poll()/select() is to wait for incoming network frames on many sockets. But TX completion for UDP/TCP frames call sock_wfree() which in turn schedules thread. When scheduled, thread does a full scan of all polled fds and can sleep again, because nothing is really available. If number of fds is large, this cause significant load. This patch makes select()/poll() aware of keyed wakeups and useless wakeups are avoided. This reduces number of context switches by about 50% on some setups, and work performed by sofirq handlers. Signed-off-by:
Eric Dumazet <dada1@cosmosbay.com> Acked-by:
David S. Miller <davem@davemloft.net> Acked-by:
Andi Kleen <ak@linux.intel.com> Acked-by:
Davide Libenzi <davidel@xmailserver.org> Cc: Christoph Lameter <cl@linux-foundation.org> Signed-off-by:
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Robert P. J. Day authored
Signed-off-by:
Robert P. J. Day <rpjday@crashcourse.ca> Cc: Anton Altaparmakov <aia21@cantab.net> Signed-off-by:
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Robert P. J. Day authored
Signed-off-by:
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Jan Blunck authored
_atomic_dec_and_lock() should not unconditionally take the lock before calling atomic_dec_and_test() in the UP case. For consistency reasons it should behave exactly like in the SMP case. Besides that this works around the problem that with CONFIG_DEBUG_SPINLOCK this spins in __spin_lock_debug() if the lock is already taken even if the counter doesn't drop to 0. Signed-off-by:
Jan Blunck <jblunck@suse.de> Acked-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by:
Nick Piggin <npiggin@suse.de> Cc: Valerie Aurora <vaurora@redhat.com> Signed-off-by:
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Dan Smith authored
The members of the new_utsname structure are defined with magic numbers that *should* correspond to the constant __NEW_UTS_LEN+1. Everywhere else, code assumes this and uses the constant, so this patch makes the structure match. Originally suggested by Serge here: https://lists.linux-foundation.org/pipermail/containers/2009-March/016258.htmlSigned-off-by:
Dan Smith <danms@us.ibm.com> Acked-by:
Serge Hallyn <serue@us.ibm.com> Signed-off-by:
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Roel Kluin authored
`ELF_CORE_COPY_REGS(x, y)' will make expansions like: `(y)[0] = (x)->x.gp[0]' but correct is `(y)[0] = (x)->regs.gp[0]' Signed-off-by:
Roel Kluin <roel.kluin@gmail.com> Cc: WANG Cong <amwang@redhat.com> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by:
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Amerigo Wang authored
When compiling uml on x86_64: MODPOST vmlinux.o WARNING: vmlinux.o (.__syscall_stub.2): unexpected non-allocatable section. Did you forget to use "ax"/"aw" in a .S file? Note that for example <linux/init.h> contains section definitions for use in .S files. Because modpost checks for missing SHF_ALLOC section flag. So just add it. Signed-off-by:
WANG Cong <amwang@redhat.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by:
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Thomas Gleixner authored
The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t) have been kept around for migration reasons. After more than two years it's time to remove them finally. This patch cleans up one of the remaining users. When all such patches hit mainline we can remove the defines and typedefs finally. Impact: cleanup Convert the last remaining users to struct irq_chip and remove the define. Signed-off-by:
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Alan Cox authored
See ancient discussion at http://marc.info/?l=user-mode-linux-devel&m=101990155831279&w=2 Addresses http://bugzilla.kernel.org/show_bug.cgi?id=7854Signed-off-by:
Alan Cox <alan@linux.intel.com> Reported-by:
Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Cc: Roland Kletzing <devzero@web.de> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by:
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Thomas Gleixner authored
The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t) have been kept around for migration reasons. After more than two years it's time to remove them finally. This patch cleans up one of the remaining users. When all such patches hit mainline we can remove the defines and typedefs finally. Impact: cleanup Convert the last remaining users to struct irq_chip and remove the define. Signed-off-by:
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Roel Kluin authored
`for_each_mem_cluster(x, y, z)' will expand to `for ((x) = (y)->x ...' but correct is `for ((x) = (y)->cluster ...' Signed-off-by:
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Thomas Gleixner authored
The defines and typedefs (hw_interrupt_type, no_irq_type, irq_desc_t) have been kept around for migration reasons. After more than two years it's time to remove them finally. This patch cleans up one of the remaining users. When all such patches hit mainline we can remove the defines and typedefs finally. Impact: cleanup Convert the last remaining users to struct irq_chip and remove the define. Signed-off-by:
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KAMEZAWA Hiroyuki authored
At lumpy reclaim, a page failed to be taken by __isolate_lru_page() can be pushed back to "src" list by list_move(). But the page may not be from "src" list. This pushes the page back to wrong LRU. And list_move() itself is unnecessary because the page is not on top of LRU. Then, leave it as it is if __isolate_lru_page() fails. Reviewed-by:
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by:
Mel Gorman <mel@csn.ul.ie> Signed-off-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
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Mel Gorman authored
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 it is possible that the heuristic will fail and the CPU gets tied up scanning uselessly. Detecting the situation requires some guesswork and experimentation so this patch adds a counter "zreclaim_failed" to /proc/vmstat. If during high CPU utilisation this counter is increasing rapidly, then the resolution to the problem may be to set /proc/sys/vm/zone_reclaim_mode to 0. [akpm@linux-foundation.org: name things consistently] Signed-off-by:
Rik van Riel <riel@redhat.com> Cc: Christoph Lameter <cl@linux-foundation.org> Reviewed-by:
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Mel Gorman authored
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. The problem is that zone_reclaim() failing at all means the zone gets marked full. This can cause situations where a zone is usable, but is being skipped because it has been considered full. Take a situation where a large tmpfs mount is occuping a large percentage of memory overall. The pages do not get cleaned or reclaimed by zone_reclaim(), but the zone gets marked full and the zonelist cache considers them not worth trying in the future. This patch makes zone_reclaim() return more fine-grained information about what occured when zone_reclaim() failued. The zone only gets marked full if it really is unreclaimable. If it's a case that the scan did not occur or if enough pages were not reclaimed with the limited reclaim_mode, then the zone is simply skipped. There is a side-effect to this patch. Currently, if zone_reclaim() successfully reclaimed SWAP_CLUSTER_MAX, an allocation attempt would go ahead. With this patch applied, zone watermarks are rechecked after zone_reclaim() does some work. This bug was introduced by commit 9276b1bc ("memory page_alloc zonelist caching speedup") way back in 2.6.19 when the zonelist_cache was introduced. It was not intended that zone_reclaim() aggressively consider the zone to be full when it failed as full direct reclaim can still be an option. Due to the age of the bug, it should be considered a -stable candidate. Signed-off-by:
Wu Fengguang <fengguang.wu@intel.com> Reviewed-by:
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Mel Gorman authored
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: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:
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Wu Fengguang authored
1) I_FREEING tests should be coupled with I_CLEAR The two I_FREEING tests are racy because clear_inode() can set i_state to I_CLEAR between the clear of I_SYNC and the test of I_FREEING. 2) skip I_WILL_FREE inodes in generic_sync_sb_inodes() to avoid possible races with generic_forget_inode() generic_forget_inode() sets I_WILL_FREE call writeback on its own, so generic_sync_sb_inodes() shall not try to step in and create possible races: generic_forget_inode inode->i_state |= I_WILL_FREE; spin_unlock(&inode_lock); generic_sync_sb_inodes() spin_lock(&inode_lock); __iget(inode); __writeback_single_inode // see non zero i_count may WARN here ==> WARN_ON(inode->i_state & I_WILL_FREE); spin_unlock(&inode_lock); may call generic_forget_inode again ==> iput(inode); The above race and warning didn't turn up because writeback_inodes() holds the s_umount lock, so generic_forget_inode() finds MS_ACTIVE and returns early. But we are not sure the UBIFS calls and future callers will guarantee that. So skip I_WILL_FREE inodes for the sake of safety. Cc: Eric Sandeen <sandeen@sandeen.net> Acked-by:Jeff Layton <jlayton@redhat.com> Cc: Masayoshi MIZUMA <m.mizuma@jp.fujitsu.com> Signed-off-by:
Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
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David Rientjes authored
When a task is chosen for oom kill and is found to be PF_EXITING, __oom_kill_task() is called to elevate the task's timeslice and give it access to memory reserves so that it may quickly exit. This privilege is unnecessary, however, if the task has already detached its mm. Although its possible for the mm to become detached later since task_lock() is not held, __oom_kill_task() will simply be a no-op in such circumstances. Subsequently, it is no longer necessary to warn about killing mm-less tasks since it is a no-op. Signed-off-by:
David Rientjes <rientjes@google.com> Acked-by:
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Daisuke Nishimura authored
Commit 2e2e4259 ("vmscan,memcg: reintroduce sc->may_swap) add may_swap flag and handle it at get_scan_ratio(). But the result of get_scan_ratio() is ignored when priority == 0, so anon lru is scanned even if may_swap == 0 or nr_swap_pages == 0. IMHO, this is not an expected behavior. As for memcg especially, because of this behavior many and many pages are swapped-out just in vain when oom is invoked by mem+swap limit. This patch is for handling may_swap flag more strictly. Signed-off-by:
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Reviewed-by:
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Wu Fengguang authored
The "move pages to active list" and "move pages to inactive list" code blocks are mostly identical and can be served by a function. Thanks to Andrew Morton for pointing this out. Note that buffer_heads_over_limit check will also be carried out for re-activated pages, which is slightly different from pre-2.6.28 kernels. Also, Rik's "vmscan: evict use-once pages first" patch could totally stop scans of active file list when memory pressure is low. So the net effect could be, the number of buffer heads is now more likely to grow large. However that's fine according to Johannes' comments: I don't think that this could be harmful. We just preserve the buffer mappings of what we consider the working set and with low memory pressure, as you say, this set is not big. As to stripping of reactivated pages: the only pages we re-activate for now are those VM_EXEC mapped ones. Since we don't expect IO from or to these pages, removing the buffer mappings in case they grow too large should be okay, I guess. Cc: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by:
Peter Zijlstra <peterz@infradead.org> Reviewed-by:
Johannes Weiner <hannes@cmpxchg.org> Signed-off-by:
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Wu Fengguang authored
Protect referenced PROT_EXEC mapped pages from being deactivated. PROT_EXEC(or its internal presentation VM_EXEC) pages normally belong to some currently running executables and their linked libraries, they shall really be cached aggressively to provide good user experiences. Thanks to Johannes Weiner for the advice to reuse the VMA walk in page_referenced() to get the PROT_EXEC bit. [more details] ( The consequences of this patch will have to be discussed together with Rik van Riel's recent patch "vmscan: evict use-once pages first". ) ( Some of the good points and insights are taken into this changelog. Thanks to all the involved people for the great LKML discussions. ) the problem =========== For a typical desktop, the most precious working set is composed of *actively accessed* (1) memory mapped executables (2) and their anonymous pages (3) and other files (4) and the dcache/icache/.. slabs while the least important data are (5) infrequently used or use-once files For a typical desktop, one major problem is busty and large amount of (5) use-once files flushing out the working set. Inside the working set, (4) dcache/icache have already been too sticky ;-) So we only have to care (2) anonymous and (1)(3) file pages. anonymous pages =============== Anonymous pages are effectively immune to the streaming IO attack, because we now have separate file/anon LRU lists. When the use-once files crowd into the file LRU, the list's "quality" is significantly lowered. Therefore the scan balance policy in get_scan_ratio() will choose to scan the (low quality) file LRU much more frequently than the anon LRU. file pages ========== Rik proposed to *not* scan the active file LRU when the inactive list grows larger than active list. This guarantees that when there are use-once streaming IO, and the working set is not too large(so that active_size < inactive_size), the active file LRU will *not* be scanned at all. So the not-too-large working set can be well protected. But there are also situations where the file working set is a bit large so that (active_size >= inactive_size), or the streaming IOs are not purely use-once. In these cases, the active list will be scanned slowly. Because the current shrink_active_list() policy is to deactivate active pages regardless of their referenced bits. The deactivated pages become susceptible to the streaming IO attack: the inactive list could be scanned fast (500MB / 50MBps = 10s) so that the deactivated pages don't have enough time to get re-referenced. Because a user tend to switch between windows in intervals from seconds to minutes. This patch holds mapped executable pages in the active list as long as they are referenced during each full scan of the active list. Because the active list is normally scanned much slower, they get longer grace time (eg. 100s) for further references, which better matches the pace of user operations. Therefore this patch greatly prolongs the in-cache time of executable code, when there are moderate memory pressures. before patch: guaranteed to be cached if reference intervals < I after patch: guaranteed to be cached if reference intervals < I+A (except when randomly reclaimed by the lumpy reclaim) where A = time to fully scan the active file LRU I = time to fully scan the inactive file LRU Note that normally A >> I. side effects ============ This patch is safe in general, it restores the pre-2.6.28 mmap() behavior but in a much smaller and well targeted scope. One may worry about some one to abuse the PROT_EXEC heuristic. But as Andrew Morton stated, there are other tricks to getting that sort of boost. Another concern is the PROT_EXEC mapped pages growing large in rare cases, and therefore hurting reclaim efficiency. But a sane application targeted for large audience will never use PROT_EXEC for data mappings. If some home made application tries to abuse that bit, it shall be aware of the consequences. If it is abused to scale of 2/3 total memory, it gains nothing but overheads. benchmarks ========== 1) memory tight desktop 1.1) brief summary - clock time and major faults are reduced by 50%; - pswpin numbers are reduced to ~1/3. That means X desktop responsiveness is doubled under high memory/swap pressure. 1.2) test scenario - nfsroot gnome desktop with 512M physical memory - run some programs, and switch between the existing windows after starting each new program. 1.3) progress timing (seconds) before after programs 0.02 0.02 N xeyes 0.75 0.76 N firefox 2.02 1.88 N nautilus 3.36 3.17 N nautilus --browser 5.26 4.89 N gthumb 7.12 6.47 N gedit 9.22 8.16 N xpdf /usr/share/doc/shared-mime-info/shared-mime-info-spec.pdf 13.58 12.55 N xterm 15.87 14.57 N mlterm 18.63 17.06 N gnome-terminal 21.16 18.90 N urxvt 26.24 23.48 N gnome-system-monitor 28.72 26.52 N gnome-help 32.15 29.65 N gnome-dictionary 39.66 36.12 N /usr/games/sol 43.16 39.27 N /usr/games/gnometris 48.65 42.56 N /usr/games/gnect 53.31 47.03 N /usr/games/gtali 58.60 52.05 N /usr/games/iagno 65.77 55.42 N /usr/games/gnotravex 70.76 61.47 N /usr/games/mahjongg 76.15 67.11 N /usr/games/gnome-sudoku 86.32 75.15 N /usr/games/glines 92.21 79.70 N /usr/games/glchess 103.79 88.48 N /usr/games/gnomine 113.84 96.51 N /usr/games/gnotski 124.40 102.19 N /usr/games/gnibbles 137.41 114.93 N /usr/games/gnobots2 155.53 125.02 N /usr/games/blackjack 179.85 135.11 N /usr/games/same-gnome 224.49 154.50 N /usr/bin/gnome-window-properties 248.44 162.09 N /usr/bin/gnome-default-applications-properties 282.62 173.29 N /usr/bin/gnome-at-properties 323.72 188.21 N /usr/bin/gnome-typing-monitor 363.99 199.93 N /usr/bin/gnome-at-visual 394.21 206.95 N /usr/bin/gnome-sound-properties 435.14 224.49 N /usr/bin/gnome-at-mobility 463.05 234.11 N /usr/bin/gnome-keybinding-properties 503.75 248.59 N /usr/bin/gnome-about-me 554.00 276.27 N /usr/bin/gnome-display-properties 615.48 304.39 N /usr/bin/gnome-network-preferences 693.03 342.01 N /usr/bin/gnome-mouse-properties 759.90 388.58 N /usr/bin/gnome-appearance-properties 937.90 508.47 N /usr/bin/gnome-control-center 1109.75 587.57 N /usr/bin/gnome-keyboard-properties 1399.05 758.16 N : oocalc 1524.64 830.03 N : oodraw 1684.31 900.03 N : ooimpress 1874.04 993.91 N : oomath 2115.12 1081.89 N : ooweb 2369.02 1161.99 N : oowriter Note that the last ": oo*" commands are actually commented out. 1.4) vmstat numbers (some relevant ones are marked with *) before after nr_free_pages 1293 3898 nr_inactive_anon 59956 53460 nr_active_anon 26815 30026 nr_inactive_file 2657 3218 nr_active_file 2019 2806 nr_unevictable 4 4 nr_mlock 4 4 nr_anon_pages 26706 27859 *nr_mapped 3542 4469 nr_file_pages 72232 67681 nr_dirty 1 0 nr_writeback 123 19 nr_slab_reclaimable 3375 3534 nr_slab_unreclaimable 11405 10665 nr_page_table_pages 8106 7864 nr_unstable 0 0 nr_bounce 0 0 *nr_vmscan_write 394776 230839 nr_writeback_temp 0 0 numa_hit 6843353 3318676 numa_miss 0 0 numa_foreign 0 0 numa_interleave 1719 1719 numa_local 6843353 3318676 numa_other 0 0 *pgpgin 5954683 2057175 *pgpgout 1578276 922744 *pswpin 1486615 512238 *pswpout 394568 230685 pgalloc_dma 277432 56602 pgalloc_dma32 6769477 3310348 pgalloc_normal 0 0 pgalloc_movable 0 0 pgfree 7048396 3371118 pgactivate 2036343 1471492 pgdeactivate 2189691 1612829 pgfault 3702176 3100702 *pgmajfault 452116 201343 pgrefill_dma 12185 7127 pgrefill_dma32 334384 653703 pgrefill_normal 0 0 pgrefill_movable 0 0 pgsteal_dma 74214 22179 pgsteal_dma32 3334164 1638029 pgsteal_normal 0 0 pgsteal_movable 0 0 pgscan_kswapd_dma 1081421 1216199 pgscan_kswapd_dma32 58979118 46002810 pgscan_kswapd_normal 0 0 pgscan_kswapd_movable 0 0 pgscan_direct_dma 2015438 1086109 pgscan_direct_dma32 55787823 36101597 pgscan_direct_normal 0 0 pgscan_direct_movable 0 0 pginodesteal 3461 7281 slabs_scanned 564864 527616 kswapd_steal 2889797 1448082 kswapd_inodesteal 14827 14835 pageoutrun 43459 21562 allocstall 9653 4032 pgrotated 384216 228631 1.5) free numbers at the end of the tests before patch: total used free shared buffers cached Mem: 474 467 7 0 0 236 -/+ buffers/cache: 230 243 Swap: 1023 418 605 after patch: total used free shared buffers cached Mem: 474 457 16 0 0 236 -/+ buffers/cache: 221 253 Swap: 1023 404 619 2) memory flushing in a file server 2.1) brief summary The number of major faults from 50 to 3 during 10% cache hot reads. That means this patch successfully stops major faults when the active file list is slowly scanned when there are partially cache hot streaming IO. 2.2) test scenario Do 100000 pread(size=110 pages, offset=(i*100) pages), where 10% of the pages will be activated: for i in `seq 0 100 10000000`; do echo $i 110; done > pattern-hot-10 iotrace.rb --load pattern-hot-10 --play /b/sparse vmmon nr_mapped nr_active_file nr_inactive_file pgmajfault pgdeactivate pgfree and monitor /proc/vmstat during the time. The test box has 2G memory. I carried out tests on fresh booted console as well as X desktop, and fetched the vmstat numbers on (1) begin: shortly after the big read IO starts; (2) end: just before the big read IO stops; (3) restore: the big read IO stops and the zsh working set restored (4) restore X: after IO, switch back and forth between the urxvt and firefox windows to restore their working set. 2.3) console mode results nr_mapped nr_active_file nr_inactive_file pgmajfault pgdeactivate pgfree 2.6.29 VM_EXEC protection ON: begin: 2481 2237 8694 630 0 574299 end: 275 231976 233914 633 776271 20933042 restore: 370 232154 234524 691 777183 20958453 2.6.29 VM_EXEC protection ON (second run): begin: 2434 2237 8493 629 0 574195 end: 284 231970 233536 632 771918 20896129 restore: 399 232218 234789 690 774526 20957909 2.6.30-rc4-mm VM_EXEC protection OFF: begin: 2479 2344 9659 210 0 579643 end: 284 232010 234142 260 772776 20917184 restore: 379 232159 234371 301 774888 20967849 The above console numbers show that - The startup pgmajfault of 2.6.30-rc4-mm is merely 1/3 that of 2.6.29. I'd attribute that improvement to the mmap readahead improvements :-) - The pgmajfault increment during the file copy is 633-630=3 vs 260-210=50. That's a huge improvement - which means with the VM_EXEC protection logic, active mmap pages is pretty safe even under partially cache hot streaming IO. - when active:inactive file lru size reaches 1:1, their scan rates is 1:20.8 under 10% cache hot IO. (computed with formula Dpgdeactivate:Dpgfree) That roughly means the active mmap pages get 20.8 more chances to get re-referenced to stay in memory. - The absolute nr_mapped drops considerably to 1/9 during the big IO, and the dropped pages are mostly inactive ones. The patch has almost no impact in this aspect, that means it won't unnecessarily increase memory pressure. (In contrast, your 20% mmap protection ratio will keep them all, and therefore eliminate the extra 41 major faults to restore working set of zsh etc.) The iotrace.rb read throughput is 151.194384MB/s 284.198252s 100001x 450560b --load pattern-hot-10 --play /b/sparse which means the inactive list is rotated at the speed of 250MB/s, so a full scan of which takes about 3.5 seconds, while a full scan of active file list takes about 77 seconds. 2.4) X mode results We can reach roughly the same conclusions for X desktop: nr_mapped nr_active_file nr_inactive_file pgmajfault pgdeactivate pgfree 2.6.30-rc4-mm VM_EXEC protection ON: begin: 9740 8920 64075 561 0 678360 end: 768 218254 220029 565 798953 21057006 restore: 857 218543 220987 606 799462 21075710 restore X: 2414 218560 225344 797 799462 21080795 2.6.30-rc4-mm VM_EXEC protection OFF: begin: 9368 5035 26389 554 0 633391 end: 770 218449 221230 661 646472 17832500 restore: 1113 218466 220978 710 649881 17905235 restore X: 2687 218650 225484 947 802700 21083584 - the absolute nr_mapped drops considerably (to 1/13 of the original size) during the streaming IO. - the delta of pgmajfault is 3 vs 107 during IO, or 236 vs 393 during the whole process. Cc: Elladan <elladan@eskimo.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Andi Kleen <andi@firstfloor.org> Cc: Christoph Lameter <cl@linux-foundation.org> Acked-by:
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