- 18 Dec, 2008 1 commit
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Paul E. McKenney authored
This patch fixes a long-standing performance bug in classic RCU that results in massive internal-to-RCU lock contention on systems with more than a few hundred CPUs. Although this patch creates a separate flavor of RCU for ease of review and patch maintenance, it is intended to replace classic RCU. This patch still handles stress better than does mainline, so I am still calling it ready for inclusion. This patch is against the -tip tree. Nevertheless, experience on an actual 1000+ CPU machine would still be most welcome. Most of the changes noted below were found while creating an rcutiny (which should permit ejecting the current rcuclassic) and while doing detailed line-by-line documentation. Updates from v9 (http://lkml.org/lkml/2008/12/2/334): o Fixes from remainder of line-by-line code walkthrough, including comment spelling, initialization, undesirable narrowing due to type conversion, removing redundant memory barriers, removing redundant local-variable initialization, and removing redundant local variables. I do not believe that any of these fixes address the CPU-hotplug issues that Andi Kleen was seeing, but please do give it a whirl in case the machine is smarter than I am. A writeup from the walkthrough may be found at the following URL, in case you are suffering from terminal insomnia or masochism: http://www.kernel.org/pub/linux/kernel/people/paulmck/tmp/rcutree-walkthrough.2008.12.16a.pdf o Made rcutree tracing use seq_file, as suggested some time ago by Lai Jiangshan. o Added a .csv variant of the rcudata debugfs trace file, to allow people having thousands of CPUs to drop the data into a spreadsheet. Tested with oocalc and gnumeric. Updated documentation to suit. Updates from v8 (http://lkml.org/lkml/2008/11/15/139): o Fix a theoretical race between grace-period initialization and force_quiescent_state() that could occur if more than three jiffies were required to carry out the grace-period initialization. Which it might, if you had enough CPUs. o Apply Ingo's printk-standardization patch. o Substitute local variables for repeated accesses to global variables. o Fix comment misspellings and redundant (but harmless) increments of ->n_rcu_pending (this latter after having explicitly added it). o Apply checkpatch fixes. Updates from v7 (http://lkml.org/lkml/2008/10/10/291): o Fixed a number of problems noted by Gautham Shenoy, including the cpu-stall-detection bug that he was having difficulty convincing me was real. ;-) o Changed cpu-stall detection to wait for ten seconds rather than three in order to reduce false positive, as suggested by Ingo Molnar. o Produced a design document (http://lwn.net/Articles/305782/). The act of writing this document uncovered a number of both theoretical and "here and now" bugs as noted below. o Fix dynticks_nesting accounting confusion, simplify WARN_ON() condition, fix kerneldoc comments, and add memory barriers in dynticks interface functions. o Add more data to tracing. o Remove unused "rcu_barrier" field from rcu_data structure. o Count calls to rcu_pending() from scheduling-clock interrupt to use as a surrogate timebase should jiffies stop counting. o Fix a theoretical race between force_quiescent_state() and grace-period initialization. Yes, initialization does have to go on for some jiffies for this race to occur, but given enough CPUs... Updates from v6 (http://lkml.org/lkml/2008/9/23/448): o Fix a number of checkpatch.pl complaints. o Apply review comments from Ingo Molnar and Lai Jiangshan on the stall-detection code. o Fix several bugs in !CONFIG_SMP builds. o Fix a misspelled config-parameter name so that RCU now announces at boot time if stall detection is configured. o Run tests on numerous combinations of configurations parameters, which after the fixes above, now build and run correctly. Updates from v5 (http://lkml.org/lkml/2008/9/15/92, bad subject line): o Fix a compiler error in the !CONFIG_FANOUT_EXACT case (blew a changeset some time ago, and finally got around to retesting this option). o Fix some tracing bugs in rcupreempt that caused incorrect totals to be printed. o I now test with a more brutal random-selection online/offline script (attached). Probably more brutal than it needs to be on the people reading it as well, but so it goes. o A number of optimizations and usability improvements: o Make rcu_pending() ignore the grace-period timeout when there is no grace period in progress. o Make force_quiescent_state() avoid going for a global lock in the case where there is no grace period in progress. o Rearrange struct fields to improve struct layout. o Make call_rcu() initiate a grace period if RCU was idle, rather than waiting for the next scheduling clock interrupt. o Invoke rcu_irq_enter() and rcu_irq_exit() only when idle, as suggested by Andi Kleen. I still don't completely trust this change, and might back it out. o Make CONFIG_RCU_TRACE be the single config variable manipulated for all forms of RCU, instead of the prior confusion. o Document tracing files and formats for both rcupreempt and rcutree. Updates from v4 for those missing v5 given its bad subject line: o Separated dynticks interface so that NMIs and irqs call separate functions, greatly simplifying it. In particular, this code no longer requires a proof of correctness. ;-) o Separated dynticks state out into its own per-CPU structure, avoiding the duplicated accounting. o The case where a dynticks-idle CPU runs an irq handler that invokes call_rcu() is now correctly handled, forcing that CPU out of dynticks-idle mode. o Review comments have been applied (thank you all!!!). For but one example, fixed the dynticks-ordering issue that Manfred pointed out, saving me much debugging. ;-) o Adjusted rcuclassic and rcupreempt to handle dynticks changes. Attached is an updated patch to Classic RCU that applies a hierarchy, greatly reducing the contention on the top-level lock for large machines. This passes 10-hour concurrent rcutorture and online-offline testing on 128-CPU ppc64 without dynticks enabled, and exposes some timekeeping bugs in presence of dynticks (exciting working on a system where "sleep 1" hangs until interrupted...), which were fixed in the 2.6.27 kernel. It is getting more reliable than mainline by some measures, so the next version will be against -tip for inclusion. See also Manfred Spraul's recent patches (or his earlier work from 2004 at http://marc.info/?l=linux-kernel&m=108546384711797&w=2 ). We will converge onto a common patch in the fullness of time, but are currently exploring different regions of the design space. That said, I have already gratefully stolen quite a few of Manfred's ideas. This patch provides CONFIG_RCU_FANOUT, which controls the bushiness of the RCU hierarchy. Defaults to 32 on 32-bit machines and 64 on 64-bit machines. If CONFIG_NR_CPUS is less than CONFIG_RCU_FANOUT, there is no hierarchy. By default, the RCU initialization code will adjust CONFIG_RCU_FANOUT to balance the hierarchy, so strongly NUMA architectures may choose to set CONFIG_RCU_FANOUT_EXACT to disable this balancing, allowing the hierarchy to be exactly aligned to the underlying hardware. Up to two levels of hierarchy are permitted (in addition to the root node), allowing up to 16,384 CPUs on 32-bit systems and up to 262,144 CPUs on 64-bit systems. I just know that I am going to regret saying this, but this seems more than sufficient for the foreseeable future. (Some architectures might wish to set CONFIG_RCU_FANOUT=4, which would limit such architectures to 64 CPUs. If this becomes a real problem, additional levels can be added, but I doubt that it will make a significant difference on real hardware.) In the common case, a given CPU will manipulate its private rcu_data structure and the rcu_node structure that it shares with its immediate neighbors. This can reduce both lock and memory contention by multiple orders of magnitude, which should eliminate the need for the strange manipulations that are reported to be required when running Linux on very large systems. Some shortcomings: o More bugs will probably surface as a result of an ongoing line-by-line code inspection. Patches will be provided as required. o There are probably hangs, rcutorture failures, &c. Seems quite stable on a 128-CPU machine, but that is kind of small compared to 4096 CPUs. However, seems to do better than mainline. Patches will be provided as required. o The memory footprint of this version is several KB larger than rcuclassic. A separate UP-only rcutiny patch will be provided, which will reduce the memory footprint significantly, even compared to the old rcuclassic. One such patch passes light testing, and has a memory footprint smaller even than rcuclassic. Initial reaction from various embedded guys was "it is not worth it", so am putting it aside. Credits: o Manfred Spraul for ideas, review comments, and bugs spotted, as well as some good friendly competition. ;-) o Josh Triplett, Ingo Molnar, Peter Zijlstra, Mathieu Desnoyers, Lai Jiangshan, Andi Kleen, Andy Whitcroft, and Andrew Morton for reviews and comments. o Thomas Gleixner for much-needed help with some timer issues (see patches below). o Jon M. Tollefson, Tim Pepper, Andrew Theurer, Jose R. Santos, Andy Whitcroft, Darrick Wong, Nishanth Aravamudan, Anton Blanchard, Dave Kleikamp, and Nathan Lynch for keeping machines alive despite my heavy abuse^Wtesting. Signed-off-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by:
Ingo Molnar <mingo@elte.hu>
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- 16 Dec, 2008 1 commit
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Paul E. McKenney authored
Impact: fix very rare reboot hang Because rcutorture ignored all signals, it does not terminate in response to the signals sent at shutdown time. This can cause strange failures due to its continuing to make use of kernel function too late in the shutdown sequence. This patch therefore adds a shutdown notifier to rcutorture, causing it to shut down in response to a reboot or an orderly shutdown. Signed-off-by:
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- 15 Dec, 2008 1 commit
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Paul Menage authored
When a cgroup is removed, it's unlinked from its parent's children list, but not actually freed until the last dentry on it is released (at which point cgrp->root->number_of_cgroups is decremented). Currently rebind_subsystems checks for the top cgroup's child list being empty in order to rebind subsystems into or out of a hierarchy - this can result in the set of subsystems bound to a hierarchy being removed-but-not-freed cgroup. The simplest fix for this is to forbid remounts that change the set of subsystems on a hierarchy that has removed-but-not-freed cgroups. This bug can be reproduced via: mkdir /mnt/cg mount -t cgroup -o ns,freezer cgroup /mnt/cg mkdir /mnt/cg/foo sleep 1h < /mnt/cg/foo & rmdir /mnt/cg/foo mount -t cgroup -o remount,ns,devices,freezer cgroup /mnt/cg kill $! Though the above will cause oops in -mm only but not mainline, but the bug can cause memory leak in mainline (and even oops) Signed-off-by:
Paul Menage <menage@google.com> Reviewed-by:
Li Zefan <lizf@cn.fujitsu.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- 14 Dec, 2008 1 commit
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Linus Torvalds authored
This reverts commit 5b7dba4f, which caused a regression in hibernate, reported by and bisected by Fabio Comolli. This revert fixes http://bugzilla.kernel.org/show_bug.cgi?id=12155 http://bugzilla.kernel.org/show_bug.cgi?id=12149 Bisected-by:
Fabio Comolli <fabio.comolli@gmail.com> Requested-by:
Rafael J. Wysocki <rjw@sisk.pl> Acked-by:
Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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- 10 Dec, 2008 3 commits
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Hugh Dickins authored
Lee Schermerhorn noticed yesterday that I broke the mapping_writably_mapped test in 2.6.7! Bad bad bug, good good find. The i_mmap_writable count must be incremented for VM_SHARED (just as i_writecount is for VM_DENYWRITE, but while holding the i_mmap_lock) when dup_mmap() copies the vma for fork: it has its own more optimal version of __vma_link_file(), and I missed this out. So the count was later going down to 0 (dangerous) when one end unmapped, then wrapping negative (inefficient) when the other end unmapped. The only impact on x86 would have been that setting a mandatory lock on a file which has at some time been opened O_RDWR and mapped MAP_SHARED (but not necessarily PROT_WRITE) across a fork, might fail with -EAGAIN when it should succeed, or succeed when it should fail. But those architectures which rely on flush_dcache_page() to flush userspace modifications back into the page before the kernel reads it, may in some cases have skipped the flush after such a fork - though any repetitive test will soon wrap the count negative, in which case it will flush_dcache_page() unnecessarily. Fix would be a two-liner, but mapping variable added, and comment moved. Reported-by:
Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by:
Hugh Dickins <hugh@veritas.com> Signed-off-by:
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Hugh Dickins authored
Miles Lane tailing /sys files hit a BUG which Pekka Enberg has tracked to my 966c8c12 sprint_symbol(): use less stack exposing a bug in slub's list_locations() - kallsyms_lookup() writes a 0 to namebuf[KSYM_NAME_LEN-1], but that was beyond the end of page provided. The 100 slop which list_locations() allows at end of page looks roughly enough for all the other stuff it might print after the symbol before it checks again: break out KSYM_SYMBOL_LEN earlier than before. Latencytop and ftrace and are using KSYM_NAME_LEN buffers where they need KSYM_SYMBOL_LEN buffers, and vmallocinfo a 2*KSYM_NAME_LEN buffer where it wants a KSYM_SYMBOL_LEN buffer: fix those before anyone copies them. [akpm@linux-foundation.org: ftrace.h needs module.h] Signed-off-by:
Pekka Enberg <penberg@cs.helsinki.fi> Acked-by:
Steven Rostedt <srostedt@redhat.com> Acked-by:
Frederic Weisbecker <fweisbec@gmail.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:
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Tom Zanussi authored
Running kmemtraced, which uses splice() on relayfs, causes a hard lock on x86-64 SMP. As described by Tom Zanussi: It looks like you hit the same problem as described here: commit 8191ecd1 splice: fix infinite loop in generic_file_splice_read() relay uses the same loop but it never got noticed or fixed. Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Tested-by:
Tom Zanussi <tzanussi@gmail.com> Signed-off-by:
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- 09 Dec, 2008 5 commits
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Brian King authored
Impact: fix possible deadlock in CPU hot-remove path This patch fixes a possible deadlock scenario in the CPU remove path. migration_call grabs rq->lock, then wakes up everything on rq->migration_queue with the lock held. Then one of the tasks on the migration queue ends up calling tg_shares_up which then also tries to acquire the same rq->lock. [c000000058eab2e0] c000000000502078 ._spin_lock_irqsave+0x98/0xf0 [c000000058eab370] c00000000008011c .tg_shares_up+0x10c/0x20c [c000000058eab430] c00000000007867c .walk_tg_tree+0xc4/0xfc [c000000058eab4d0] c0000000000840c8 .try_to_wake_up+0xb0/0x3c4 [c000000058eab590] c0000000000799a0 .__wake_up_common+0x6c/0xe0 [c000000058eab640] c00000000007ada4 .complete+0x54/0x80 [c000000058eab6e0] c000000000509fa8 .migration_call+0x5fc/0x6f8 [c000000058eab7c0] c000000000504074 .notifier_call_chain+0x68/0xe0 [c000000058eab860] c000000000506568 ._cpu_down+0x2b0/0x3f4 [c000000058eaba60] c000000000506750 .cpu_down+0xa4/0x108 [c000000058eabb10] c000000000507e54 .store_online+0x44/0xa8 [c000000058eabba0] c000000000396260 .sysdev_store+0x3c/0x50 [c000000058eabc10] c0000000001a39b8 .sysfs_write_file+0x124/0x18c [c000000058eabcd0] c00000000013061c .vfs_write+0xd0/0x1bc [c000000058eabd70] c0000000001308a4 .sys_write+0x68/0x114 [c000000058eabe30] c0000000000086b4 syscall_exit+0x0/0x40 Signed-off-by:
Brian King <brking@linux.vnet.ibm.com> Acked-by:
Peter Zijlstra <peterz@infradead.org> Signed-off-by:
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Al Viro authored
Timestamp in audit_context is valid only if ->in_syscall is set. Signed-off-by:Al Viro <viro@zeniv.linux.org.uk>
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Randy Dunlap authored
Delete excess kernel-doc notation in kernel/auditsc.c: Warning(linux-2.6.27-git10//kernel/auditsc.c:1481): Excess function parameter or struct member 'tsk' description in 'audit_syscall_entry' Warning(linux-2.6.27-git10//kernel/auditsc.c:1564): Excess function parameter or struct member 'tsk' description in 'audit_syscall_exit' Signed-off-by:
Randy Dunlap <randy.dunlap@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric Paris <eparis@redhat.com> Signed-off-by:
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Al Viro authored
Signed-off-by: -
Eric Paris authored
Currently audit=0 on the kernel command line does absolutely nothing. Audit always loads and always uses its resources such as creating the kernel netlink socket. This patch causes audit=0 to actually disable audit. Audit will use no resources and starting the userspace auditd daemon will not cause the kernel audit system to activate. Signed-off-by:
Eric Paris <eparis@redhat.com> Signed-off-by:
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- 04 Dec, 2008 2 commits
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Al Viro authored
it had been put there to mark the call of blkdev_put() that needed proper argument propagated to it; later patch in the same series had done just that. Signed-off-by: -
john stultz authored
Impact: fix time warp bug Alex Shi, along with Yanmin Zhang have been noticing occasional time inconsistencies recently. Through their great diagnosis, they found that the xtime_nsec value used in update_wall_time was occasionally going negative. After looking through the code for awhile, I realized we have the possibility for an underflow when three conditions are met in update_wall_time(): 1) We have accumulated a second's worth of nanoseconds, so we incremented xtime.tv_sec and appropriately decrement xtime_nsec. (This doesn't cause xtime_nsec to go negative, but it can cause it to be small). 2) The remaining offset value is large, but just slightly less then cycle_interval. 3) clocksource_adjust() is speeding up the clock, causing a corrective amount (compensating for the increase in the multiplier being multiplied against the unaccumulated offset value) to be subtracted from xtime_nsec. This can cause xtime_nsec to underflow. Unfortunately, since we notify the NTP subsystem via second_overflow() whenever we accumulate a full second, and this effects the error accumulation that has already occured, we cannot simply revert the accumulated second from xtime nor move the second accumulation to after the clocksource_adjust call without a change in behavior. This leaves us with (at least) two options: 1) Simply return from clocksource_adjust() without making a change if we notice the adjustment would cause xtime_nsec to go negative. This would work, but I'm concerned that if a large adjustment was needed (due to the error being large), it may be possible to get stuck with an ever increasing error that becomes too large to correct (since it may always force xtime_nsec negative). This may just be paranoia on my part. 2) Catch xtime_nsec if it is negative, then add back the amount its negative to both xtime_nsec and the error. This second method is consistent with how we've handled earlier rounding issues, and also has the benefit that the error being added is always in the oposite direction also always equal or smaller then the correction being applied. So the risk of a corner case where things get out of control is lessened. This patch fixes bug 11970, as tested by Yanmin Zhang http://bugzilla.kernel.org/show_bug.cgi?id=11970 Reported-by: alex.shi@intel.com Signed-off-by:John Stultz <johnstul@us.ibm.com> Acked-by:
"Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Tested-by:
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- 03 Dec, 2008 1 commit
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Roel Kluin authored
Impact: fix warnings-limit cutoff check for debug feature unsigned sysctl_hung_task_warnings cannot be less than 0 Signed-off-by:
Roel Kluin <roel.kluin@gmail.com> Signed-off-by:
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- 01 Dec, 2008 2 commits
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Arjan van de Ven authored
The description for 'D' was missing in the comment... (causing me a minute of WTF followed by looking at more of the code) Signed-off-by:
Arjan van de Ven <arjan@linux.intel.com> Signed-off-by:
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Davide Libenzi authored
It has been thought that the per-user file descriptors limit would also limit the resources that a normal user can request via the epoll interface. Vegard Nossum reported a very simple program (a modified version attached) that can make a normal user to request a pretty large amount of kernel memory, well within the its maximum number of fds. To solve such problem, default limits are now imposed, and /proc based configuration has been introduced. A new directory has been created, named /proc/sys/fs/epoll/ and inside there, there are two configuration points: max_user_instances = Maximum number of devices - per user max_user_watches = Maximum number of "watched" fds - per user The current default for "max_user_watches" limits the memory used by epoll to store "watches", to 1/32 of the amount of the low RAM. As example, a 256MB 32bit machine, will have "max_user_watches" set to roughly 90000. That should be enough to not break existing heavy epoll users. The default value for "max_user_instances" is set to 128, that should be enough too. This also changes the userspace, because a new error code can now come out from EPOLL_CTL_ADD (-ENOSPC). The EMFILE from epoll_create() was already listed, so that should be ok. [akpm@linux-foundation.org: use get_current_user()] Signed-off-by:
Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: <stable@kernel.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Reported-by:
Vegard Nossum <vegardno@ifi.uio.no> Signed-off-by:
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- 30 Nov, 2008 2 commits
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Christoph Hellwig authored
All architectures now use the generic compat_sys_ptrace, as should every new architecture that needs 32bit compat (if we'll ever get another). Remove the now superflous __ARCH_WANT_COMPAT_SYS_PTRACE define, and also kill a comment about __ARCH_SYS_PTRACE that was added after __ARCH_SYS_PTRACE was already gone. Signed-off-by:
Christoph Hellwig <hch@lst.de> Acked-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
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Al Viro authored
Signed-off-by:
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- 29 Nov, 2008 2 commits
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Ingo Molnar authored
Regarding the bug addressed in: 4cd42620 : sched: prevent divide by zero error in cpu_avg_load_per_task Linus points out that the fix is not complete: > There's nothing that keeps gcc from deciding not to reload > rq->nr_running. > > Of course, in _practice_, I don't think gcc ever will (if it decides > that it will spill, gcc is likely going to decide that it will > literally spill the local variable to the stack rather than decide to > reload off the pointer), but it's a valid compiler optimization, and > it even has a name (rematerialization). > > So I suspect that your patch does fix the bug, but it still leaves the > fairly unlikely _potential_ for it to re-appear at some point. > > We have ACCESS_ONCE() as a macro to guarantee that the compiler > doesn't rematerialize a pointer access. That also would clarify > the fact that we access something unsafe outside a lock. So make sure our nr_running value is immutable and cannot change after we check it for nonzero. Signed-off-by:
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Ingo Molnar authored
this warning: kernel/cpuset.c: In function ‘generate_sched_domains’: kernel/cpuset.c:588: warning: ‘ndoms’ may be used uninitialized in this function triggers because GCC does not recognize that ndoms stays uninitialized only if doms is NULL - but that flow is covered at the end of generate_sched_domains(). Help out GCC by initializing this variable to 0. (that's prudent anyway) Also, this function needs a splitup and code flow simplification: with 160 lines length it's clearly too long. Signed-off-by:
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- 27 Nov, 2008 2 commits
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Steven Rostedt authored
Impact: fix divide by zero crash in scheduler rebalance irq While testing the branch profiler, I hit this crash: divide error: 0000 [#1] PREEMPT SMP [...] RIP: 0010:[<ffffffff8024a008>] [<ffffffff8024a008>] cpu_avg_load_per_task+0x50/0x7f [...] Call Trace: <IRQ> <0> [<ffffffff8024fd43>] find_busiest_group+0x3e5/0xcaa [<ffffffff8025da75>] rebalance_domains+0x2da/0xa21 [<ffffffff80478769>] ? find_next_bit+0x1b2/0x1e6 [<ffffffff8025e2ce>] run_rebalance_domains+0x112/0x19f [<ffffffff8026d7c2>] __do_softirq+0xa8/0x232 [<ffffffff8020ea7c>] call_softirq+0x1c/0x3e [<ffffffff8021047a>] do_softirq+0x94/0x1cd [<ffffffff8026d5eb>] irq_exit+0x6b/0x10e [<ffffffff8022e6ec>] smp_apic_timer_interrupt+0xd3/0xff [<ffffffff8020e4b3>] apic_timer_interrupt+0x13/0x20 The code for cpu_avg_load_per_task has: if (rq->nr_running) rq->avg_load_per_task = rq->load.weight / rq->nr_running; The runqueue lock is not held here, and there is nothing that prevents the rq->nr_running from going to zero after it passes the if condition. The branch profiler simply made the race window bigger. This patch saves off the rq->nr_running to a local variable and uses that for both the condition and the division. Signed-off-by:
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Lai Jiangshan authored
Impact: prevent unnecessary stack recursion if the resched flag was set before we entered, then don't reschedule. Signed-off-by:
Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by:
Steven Rostedt <rostedt@goodmis.org> Signed-off-by:
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- 24 Nov, 2008 1 commit
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Petr Tesarik authored
Since CLOCK_PROCESS_CPUTIME_ID is in fact translated to -6, the switch statement in cpu_clock_sample_group() must first mask off the irrelevant bits, similar to cpu_clock_sample(). Signed-off-by:
Petr Tesarik <ptesarik@suse.cz> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> -- posix-cpu-timers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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- 23 Nov, 2008 1 commit
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Pekka Paalanen authored
Impact: fix mmiotrace overrun tracing When ftrace framework moved to use the ring buffer facility, the buffer overrun detection was broken after 2.6.27 by commit | commit 3928a8a2 | Author: Steven Rostedt <rostedt@goodmis.org> | Date: Mon Sep 29 23:02:41 2008 -0400 | | ftrace: make work with new ring buffer | | This patch ports ftrace over to the new ring buffer. The detection is now fixed by using the ring buffer API. When mmiotrace detects a buffer overrun, it will report the number of lost events. People reading an mmiotrace log must know if something was missed, otherwise the data may not make sense. Signed-off-by:
Pekka Paalanen <pq@iki.fi> Acked-by:
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- 21 Nov, 2008 2 commits
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Li Zefan authored
Impact: prettify /proc/lockdep_info Just feel odd that not all lines of lockdep info are aligned. Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by:
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Liming Wang authored
Impact: make output of stack_trace complete if buffer overruns When read buffer overruns, the output of stack_trace isn't complete. When printing records with seq_printf in t_show, if the read buffer has overruned by the current record, then this record won't be printed to user space through read buffer, it will just be dropped in this printing. When next printing, t_start should return the "*pos"th record, which is the one dropped by previous printing, but it just returns (m->private + *pos)th record. Here we use a more sane method to implement seq_operations which can be found in kernel code. Thus we needn't initialize m->private. About testing, it's not easy to overrun read buffer, but we can use seq_printf to print more padding bytes in t_show, then it's easy to check whether or not records are lost. This commit has been tested on both condition of overrun and non overrun. Signed-off-by:
Liming Wang <liming.wang@windriver.com> Acked-by:
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- 19 Nov, 2008 8 commits
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Li Zefan authored
Try this, and you'll get oops immediately: # cd Documentation/accounting/ # gcc -o getdelays getdelays.c # mount -t cgroup -o debug xxx /mnt # ./getdelays -C /mnt/tasks Because a normal file's dentry->d_fsdata is a pointer to struct cftype, not struct cgroup. After the patch, it returns EINVAL if we try to get cgroupstats from a normal file. Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by:
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Hugh Dickins authored
sprint_symbol(), itself used when dumping stacks, has been wasting 128 bytes of stack: lookup the symbol directly into the buffer supplied by the caller, instead of using a locally declared namebuf. I believe the name != buffer strcpy() is obsolete: the design here dates from when module symbol lookup pointed into a supposedly const but sadly volatile table; nowadays it copies, but an uncalled strcpy() looks better here than the risk of a recursive BUG_ON(). Signed-off-by:
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KAMEZAWA Hiroyuki authored
As Balbir pointed out, memcg's pre_destroy handler has potential deadlock. It has following lock sequence. cgroup_mutex (cgroup_rmdir) -> pre_destroy -> mem_cgroup_pre_destroy-> force_empty -> cpu_hotplug.lock. (lru_add_drain_all-> schedule_work-> get_online_cpus) But, cpuset has following. cpu_hotplug.lock (call notifier) -> cgroup_mutex. (within notifier) Then, this lock sequence should be fixed. Considering how pre_destroy works, it's not necessary to holding cgroup_mutex() while calling it. As a side effect, we don't have to wait at this mutex while memcg's force_empty works.(it can be long when there are tons of pages.) Signed-off-by:KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by:
Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by:
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Miao Xie authored
After adding a node into the machine, top cpuset's mems isn't updated. By reviewing the code, we found that the update function cpuset_track_online_nodes() was invoked after node_states[N_ONLINE] changes. It is wrong because N_ONLINE just means node has pgdat, and if node has/added memory, we use N_HIGH_MEMORY. So, We should invoke the update function after node_states[N_HIGH_MEMORY] changes, just like its commit says. This patch fixes it. And we use notifier of memory hotplug instead of direct calling of cpuset_track_online_nodes(). Signed-off-by:
Miao Xie <miaox@cn.fujitsu.com> Acked-by:
Yasunori Goto <y-goto@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Paul Menage <menage@google.com Signed-off-by:
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Ulrich Drepper authored
Introduce a new accept4() system call. The addition of this system call matches analogous changes in 2.6.27 (dup3(), evenfd2(), signalfd4(), inotify_init1(), epoll_create1(), pipe2()) which added new system calls that differed from analogous traditional system calls in adding a flags argument that can be used to access additional functionality. The accept4() system call is exactly the same as accept(), except that it adds a flags bit-mask argument. Two flags are initially implemented. (Most of the new system calls in 2.6.27 also had both of these flags.) SOCK_CLOEXEC causes the close-on-exec (FD_CLOEXEC) flag to be enabled for the new file descriptor returned by accept4(). This is a useful security feature to avoid leaking information in a multithreaded program where one thread is doing an accept() at the same time as another thread is doing a fork() plus exec(). More details here: http://udrepper.livejournal.com/20407.html "Secure File Descriptor Handling", Ulrich Drepper). The other flag is SOCK_NONBLOCK, which causes the O_NONBLOCK flag to be enabled on the new open file description created by accept4(). (This flag is merely a convenience, saving the use of additional calls fcntl(F_GETFL) and fcntl (F_SETFL) to achieve the same result. Here's a test program. Works on x86-32. Should work on x86-64, but I (mtk) don't have a system to hand to test with. It tests accept4() with each of the four possible combinations of SOCK_CLOEXEC and SOCK_NONBLOCK set/clear in 'flags', and verifies that the appropriate flags are set on the file descriptor/open file description returned by accept4(). I tested Ulrich's patch in this thread by applying against 2.6.28-rc2, and it passes according to my test program. /* test_accept4.c Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk <mtk.manpages@gmail.com> Licensed under the GNU GPLv2 or later. */ #define _GNU_SOURCE #include <unistd.h> #include <sys/syscall.h> #include <sys/socket.h> #include <netinet/in.h> #include <stdlib.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #define PORT_NUM 33333 #define die(msg) do { perror(msg); exit(EXIT_FAILURE); } while (0) /**********************************************************************/ /* The following is what we need until glibc gets a wrapper for accept4() */ /* Flags for socket(), socketpair(), accept4() */ #ifndef SOCK_CLOEXEC #define SOCK_CLOEXEC O_CLOEXEC #endif #ifndef SOCK_NONBLOCK #define SOCK_NONBLOCK O_NONBLOCK #endif #ifdef __x86_64__ #define SYS_accept4 288 #elif __i386__ #define USE_SOCKETCALL 1 #define SYS_ACCEPT4 18 #else #error "Sorry -- don't know the syscall # on this architecture" #endif static int accept4(int fd, struct sockaddr *sockaddr, socklen_t *addrlen, int flags) { printf("Calling accept4(): flags = %x", flags); if (flags != 0) { printf(" ("); if (flags & SOCK_CLOEXEC) printf("SOCK_CLOEXEC"); if ((flags & SOCK_CLOEXEC) && (flags & SOCK_NONBLOCK)) printf(" "); if (flags & SOCK_NONBLOCK) printf("SOCK_NONBLOCK"); printf(")"); } printf("\n"); #if USE_SOCKETCALL long args[6]; args[0] = fd; args[1] = (long) sockaddr; args[2] = (long) addrlen; args[3] = flags; return syscall(SYS_socketcall, SYS_ACCEPT4, args); #else return syscall(SYS_accept4, fd, sockaddr, addrlen, flags); #endif } /**********************************************************************/ static int do_test(int lfd, struct sockaddr_in *conn_addr, int closeonexec_flag, int nonblock_flag) { int connfd, acceptfd; int fdf, flf, fdf_pass, flf_pass; struct sockaddr_in claddr; socklen_t addrlen; printf("=======================================\n"); connfd = socket(AF_INET, SOCK_STREAM, 0); if (connfd == -1) die("socket"); if (connect(connfd, (struct sockaddr *) conn_addr, sizeof(struct sockaddr_in)) == -1) die("connect"); addrlen = sizeof(struct sockaddr_in); acceptfd = accept4(lfd, (struct sockaddr *) &claddr, &addrlen, closeonexec_flag | nonblock_flag); if (acceptfd == -1) { perror("accept4()"); close(connfd); return 0; } fdf = fcntl(acceptfd, F_GETFD); if (fdf == -1) die("fcntl:F_GETFD"); fdf_pass = ((fdf & FD_CLOEXEC) != 0) == ((closeonexec_flag & SOCK_CLOEXEC) != 0); printf("Close-on-exec flag is %sset (%s); ", (fdf & FD_CLOEXEC) ? "" : "not ", fdf_pass ? "OK" : "failed"); flf = fcntl(acceptfd, F_GETFL); if (flf == -1) die("fcntl:F_GETFD"); flf_pass = ((flf & O_NONBLOCK) != 0) == ((nonblock_flag & SOCK_NONBLOCK) !=0); printf("nonblock flag is %sset (%s)\n", (flf & O_NONBLOCK) ? "" : "not ", flf_pass ? "OK" : "failed"); close(acceptfd); close(connfd); printf("Test result: %s\n", (fdf_pass && flf_pass) ? "PASS" : "FAIL"); return fdf_pass && flf_pass; } static int create_listening_socket(int port_num) { struct sockaddr_in svaddr; int lfd; int optval; memset(&svaddr, 0, sizeof(struct sockaddr_in)); svaddr.sin_family = AF_INET; svaddr.sin_addr.s_addr = htonl(INADDR_ANY); svaddr.sin_port = htons(port_num); lfd = socket(AF_INET, SOCK_STREAM, 0); if (lfd == -1) die("socket"); optval = 1; if (setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) == -1) die("setsockopt"); if (bind(lfd, (struct sockaddr *) &svaddr, sizeof(struct sockaddr_in)) == -1) die("bind"); if (listen(lfd, 5) == -1) die("listen"); return lfd; } int main(int argc, char *argv[]) { struct sockaddr_in conn_addr; int lfd; int port_num; int passed; passed = 1; port_num = (argc > 1) ? atoi(argv[1]) : PORT_NUM; memset(&conn_addr, 0, sizeof(struct sockaddr_in)); conn_addr.sin_family = AF_INET; conn_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); conn_addr.sin_port = htons(port_num); lfd = create_listening_socket(port_num); if (!do_test(lfd, &conn_addr, 0, 0)) passed = 0; if (!do_test(lfd, &conn_addr, SOCK_CLOEXEC, 0)) passed = 0; if (!do_test(lfd, &conn_addr, 0, SOCK_NONBLOCK)) passed = 0; if (!do_test(lfd, &conn_addr, SOCK_CLOEXEC, SOCK_NONBLOCK)) passed = 0; close(lfd); exit(passed ? EXIT_SUCCESS : EXIT_FAILURE); } [mtk.manpages@gmail.com: rewrote changelog, updated test program] Signed-off-by:
Ulrich Drepper <drepper@redhat.com> Tested-by:
Michael Kerrisk <mtk.manpages@gmail.com> Acked-by:
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Steven Rostedt authored
Impact: clean up and fix for dyn ftrace filter selection The previous logic of the dynamic ftrace selection of enabling or disabling functions was complex and incorrect. This patch simplifies the code and corrects the usage. This simplification also makes the code more robust. Here is the correct logic: Given a function that can be traced by dynamic ftrace: If the function is not to be traced, disable it if it was enabled. (this is if the function is in the set_ftrace_notrace file) (filter is on if there exists any functions in set_ftrace_filter file) If the filter is on, and we are enabling functions: If the function is in set_ftrace_filter, enable it if it is not already enabled. If the function is not in set_ftrace_filter, disable it if it is not already disabled. Otherwise, if the filter is off and we are enabling function tracing: Enable the function if it is not already enabled. Otherwise, if we are disabling function tracing: Disable the function if it is not already disabled. This code now sets or clears the ENABLED flag in the record, and at the end it will enable the function if the flag is set, or disable the function if the flag is cleared. The parameters for the function that does the above logic is also simplified. Instead of passing in confusing "new" and "old" where they might be swapped if the "enabled" flag is not set. The old logic even had one of the above always NULL and had to be filled in. The new logic simply passes in one parameter called "nop". A "call" is calculated in the code, and at the end of the logic, when we know we need to either disable or enable the function, we can then use the "nop" and "call" properly. This code is more robust than the previous version. Signed-off-by: -
Steven Rostedt authored
Impact: fix filter selection to apply when set It can be confusing when the set_filter_functions is set (or cleared) and the functions being recorded by the dynamic tracer does not match. This patch causes the code to be updated if the function tracer is enabled and the filter is changed. Signed-off-by:
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Steven Rostedt authored
Impact: fix of output of set_ftrace_filter The commit "ftrace: do not show freed records in available_filter_functions" Removed a bit too much from the set_ftrace_filter code, where we now see all functions in the set_ftrace_filter file even when we set a filter. Signed-off-by:
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- 18 Nov, 2008 5 commits
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Vegard Nossum authored
Impact: fix tracing buffer mutex leak in case of allocation failure This error was spotted by this semantic patch: http://www.emn.fr/x-info/coccinelle/mut.html It looks correct as far as I can tell. Please review. Signed-off-by:
Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by:
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Arjan van de Ven authored
By using WARN(), kerneloops.org can collect which component is causing the delay and make statistics about that. suspend_test_finish() is currently the number 2 item but unless we can collect who's causing it we're not going to be able to fix the hot topic ones.. Signed-off-by:
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Julia Lawall authored
Impact: fix memory leak Error handling code following a kzalloc should free the allocated data. The semantic match that finds the problem is as follows: (http://www.emn.fr/x-info/coccinelle/ ) // <smpl> @r exists@ local idexpression x; statement S; expression E; identifier f,l; position p1,p2; expression *ptr != NULL; @@ ( if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) == NULL) S | x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...); ... if (x == NULL) S ) <... when != x when != if (...) { <+...x...+> } x->f = E ...> ( return \(0\|<+...x...+>\|ptr\); | return@p2 ...; ) @script:python@ p1 << r.p1; p2 << r.p2; @@ print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line) // </smpl> Signed-off-by:
Julia Lawall <julia@diku.dk> Signed-off-by:
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Lai Jiangshan authored
relay_open() will close allocated buffers when failed. but if cpu offlined, some buffer will not be closed. this patch fixed it. and did cleanup for relay_reset() too. Signed-off-by:
Jens Axboe <jens.axboe@oracle.com>
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Rakib Mullick authored
Impact: fix section mismatch warning in kernel/profile.c Here, profile_nop function has been called from a non-init function create_hash_tables(void). Which generetes a section mismatch warning. Previously, create_hash_tables(void) was a init function. So, removing __init from create_hash_tables(void) requires profile_nop to be non-init. This patch makes profile_nop function inline and fixes the following warning: WARNING: vmlinux.o(.text+0x6ebb6): Section mismatch in reference from the function create_hash_tables() to the function .init.text:profile_nop() The function create_hash_tables() references the function __init profile_nop(). This is often because create_hash_tables lacks a __init annotation or the annotation of profile_nop is wrong. Signed-off-by:
Rakib Mullick <rakib.mullick@gmail.com> Signed-off-by:
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