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2016-02-18signals, pkeys: Notify userspace about protection key faultsDave Hansen1-0/+4
A protection key fault is very similar to any other access error. There must be a VMA, etc... We even want to take the same action (SIGSEGV) that we do with a normal access fault. However, we do need to let userspace know that something is different. We do this the same way what we did with SEGV_BNDERR with Memory Protection eXtensions (MPX): define a new SEGV code: SEGV_PKUERR. We add a siginfo field: si_pkey that reveals to userspace which protection key was set on the PTE that we faulted on. There is no other easy way for userspace to figure this out. They could parse smaps but that would be a bit cruel. We share space with in siginfo with _addr_bnd. #BR faults from MPX are completely separate from page faults (#PF) that trigger from protection key violations, so we never need both at the same time. Note that _pkey is a 64-bit value. The current hardware only supports 4-bit protection keys. We do this because there is _plenty_ of space in _sigfault and it is possible that future processors would support more than 4 bits of protection keys. The x86 code to actually fill in the siginfo is in the next patch. Signed-off-by: Dave Hansen <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Al Viro <[email protected]> Cc: Amanieu d'Antras <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Palmer Dabbelt <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Richard Weinberger <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Sasha Levin <[email protected]> Cc: Vegard Nossum <[email protected]> Cc: Vladimir Davydov <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17workqueue: Replace usage of init_name with dev_set_name()Lars-Peter Clausen1-1/+1
The init_name property of the device struct is sort of a hack and should only be used for statically allocated devices. Since the device is dynamically allocated here it is safe to use the proper way to set a devices name by calling dev_set_name(). Signed-off-by: Lars-Peter Clausen <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
2016-02-17ftrace/module: remove ftrace module notifierJessica Yu2-35/+5
Remove the ftrace module notifier in favor of directly calling ftrace_module_enable() and ftrace_release_mod() in the module loader. Hard-coding the function calls directly in the module loader removes dependence on the module notifier call chain and provides better visibility and control over what gets called when, which is important to kernel utilities such as livepatch. This fixes a notifier ordering issue in which the ftrace module notifier (and hence ftrace_module_enable()) for coming modules was being called after klp_module_notify(), which caused livepatch modules to initialize incorrectly. This patch removes dependence on the module notifier call chain in favor of hard coding the corresponding function calls in the module loader. This ensures that ftrace and livepatch code get called in the correct order on patch module load and unload. Fixes: 5156dca34a3e ("ftrace: Fix the race between ftrace and insmod") Signed-off-by: Jessica Yu <[email protected]> Reviewed-by: Steven Rostedt <[email protected]> Reviewed-by: Petr Mladek <[email protected]> Acked-by: Rusty Russell <[email protected]> Reviewed-by: Josh Poimboeuf <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Jiri Kosina <[email protected]>
2016-02-17futex: Remove requirement for lock_page() in get_futex_key()Mel Gorman1-8/+91
When dealing with key handling for shared futexes, we can drastically reduce the usage/need of the page lock. 1) For anonymous pages, the associated futex object is the mm_struct which does not require the page lock. 2) For inode based, keys, we can check under RCU read lock if the page mapping is still valid and take reference to the inode. This just leaves one rare race that requires the page lock in the slow path when examining the swapcache. Additionally realtime users currently have a problem with the page lock being contended for unbounded periods of time during futex operations. Task A get_futex_key() lock_page() ---> preempted Now any other task trying to lock that page will have to wait until task A gets scheduled back in, which is an unbound time. With this patch, we pretty much have a lockless futex_get_key(). Experiments show that this patch can boost/speedup the hashing of shared futexes with the perf futex benchmarks (which is good for measuring such change) by up to 45% when there are high (> 100) thread counts on a 60 core Westmere. Lower counts are pretty much in the noise range or less than 10%, but mid range can be seen at over 30% overall throughput (hash ops/sec). This makes anon-mem shared futexes much closer to its private counterpart. Signed-off-by: Mel Gorman <[email protected]> [ Ported on top of thp refcount rework, changelog, comments, fixes. ] Signed-off-by: Davidlohr Bueso <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Chris Mason <[email protected]> Cc: Darren Hart <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17futex: Rename barrier references in ordering guaranteesDavidlohr Bueso1-17/+17
Ingo suggested we rename how we reference barriers A and B regarding futex ordering guarantees. This patch replaces, for both barriers, MB (A) with smp_mb(); (A), such that: - We explicitly state that the barriers are SMP, and - We standardize how we reference these across futex.c helping readers follow what barrier does what and where. Suggested-by: Ingo Molnar <[email protected]> Signed-off-by: Davidlohr Bueso <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Chris Mason <[email protected]> Cc: Darren Hart <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17perf/core: Remove unused arguments from a bunch of functionsThomas Gleixner1-11/+10
No functional change, just less confusing to read. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Vince Weaver <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17Merge branch 'perf/urgent' into perf/core, to queue up dependent patchIngo Molnar9-118/+250
Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17perf/core: Plug potential memory leak in CPU_UP_PREPAREThomas Gleixner1-1/+1
If CPU_UP_PREPARE is called it is not guaranteed, that a previously allocated and assigned hash has been freed already, but perf_event_init_cpu() unconditionally allocates and assignes a new hash if the swhash is referenced. By overwriting the pointer the existing hash is not longer accessible. Verify that there is no hash assigned on this cpu before allocating and assigning a new one. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Vince Weaver <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17perf/core: Remove the bogus and dangerous CPU_DOWN_FAILED hotplug stateThomas Gleixner1-1/+0
If CPU_DOWN_PREPARE fails the perf hotplug notifier is called for CPU_DOWN_FAILED and calls perf_event_init_cpu(), which checks whether the swhash is referenced. If yes it allocates a new hash and stores the pointer in the per cpu data structure. But at this point the cpu is still online, so there must be a valid hash already. By overwriting the pointer the existing hash is not longer accessible. Remove the CPU_DOWN_FAILED state, as there is nothing to (re)allocate. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Vince Weaver <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17perf/core: Remove bogus UP_CANCELED hotplug stateThomas Gleixner1-1/+0
If CPU_UP_PREPARE fails the perf hotplug code calls perf_event_exit_cpu(), which is a pointless exercise. The cpu is not online, so the smp function calls return -ENXIO. So the result is a list walk to call noops. Remove it. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Vince Weaver <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17sched/deadline: Fix trivial typo in printk() messageSteven Rostedt1-1/+1
It's "too much" not "to much". Signed-off-by: Steven Rostedt <[email protected]> Acked-by: Juri Lelli <[email protected]> Cc: Jiri Kosina <[email protected]> Cc: Juri Lelli <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-17sched/core: Remove dead statement in __schedule()Byungchul Park1-1/+0
Remove an unnecessary assignment of variable not used any more. ( This has no runtime effects as GCC is smart enough to optimize this out. ) Signed-off-by: Byungchul Park <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] [ Edited the changelog. ] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-16Add FS_USERNS_FLAG to cgroup fsSerge Hallyn1-0/+2
allowing root in a non-init user namespace to mount it. This should now be safe, because 1. non-init-root cannot mount a previously unbound subsystem 2. the task doing the mount must be privileged with respect to the user namespace owning the cgroup namespace 3. the mounted subsystem will have its current cgroup as the root dentry. the permissions will be unchanged, so tasks will receive no new privilege over the cgroups which they did not have on the original mounts. Signed-off-by: Serge Hallyn <[email protected]>
2016-02-16cgroup: mount cgroupns-root when inside non-init cgroupnsSerge Hallyn1-1/+47
This patch enables cgroup mounting inside userns when a process as appropriate privileges. The cgroup filesystem mounted is rooted at the cgroupns-root. Thus, in a container-setup, only the hierarchy under the cgroupns-root is exposed inside the container. This allows container management tools to run inside the containers without depending on any global state. Signed-off-by: Serge Hallyn <[email protected]> Signed-off-by: Tejun Heo <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
2016-02-16cgroup: cgroup namespace setns supportAditya Kali1-3/+16
setns on a cgroup namespace is allowed only if task has CAP_SYS_ADMIN in its current user-namespace and over the user-namespace associated with target cgroupns. No implicit cgroup changes happen with attaching to another cgroupns. It is expected that the somone moves the attaching process under the target cgroupns-root. Signed-off-by: Aditya Kali <[email protected]> Signed-off-by: Serge E. Hallyn <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
2016-02-16cgroup: introduce cgroup namespacesAditya Kali4-10/+192
Introduce the ability to create new cgroup namespace. The newly created cgroup namespace remembers the cgroup of the process at the point of creation of the cgroup namespace (referred as cgroupns-root). The main purpose of cgroup namespace is to virtualize the contents of /proc/self/cgroup file. Processes inside a cgroup namespace are only able to see paths relative to their namespace root (unless they are moved outside of their cgroupns-root, at which point they will see a relative path from their cgroupns-root). For a correctly setup container this enables container-tools (like libcontainer, lxc, lmctfy, etc.) to create completely virtualized containers without leaking system level cgroup hierarchy to the task. This patch only implements the 'unshare' part of the cgroupns. Signed-off-by: Aditya Kali <[email protected]> Signed-off-by: Serge Hallyn <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
2016-02-16mm/gup: Introduce get_user_pages_remote()Dave Hansen1-2/+8
For protection keys, we need to understand whether protections should be enforced in software or not. In general, we enforce protections when working on our own task, but not when on others. We call these "current" and "remote" operations. This patch introduces a new get_user_pages() variant: get_user_pages_remote() Which is a replacement for when get_user_pages() is called on non-current tsk/mm. We also introduce a new gup flag: FOLL_REMOTE which can be used for the "__" gup variants to get this new behavior. The uprobes is_trap_at_addr() location holds mmap_sem and calls get_user_pages(current->mm) on an instruction address. This makes it a pretty unique gup caller. Being an instruction access and also really originating from the kernel (vs. the app), I opted to consider this a 'remote' access where protection keys will not be enforced. Without protection keys, this patch should not change any behavior. Signed-off-by: Dave Hansen <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Naoya Horiguchi <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Srikar Dronamraju <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-15treewide: Fix typo in printkMasanari Iida1-1/+1
This patch fix spelling typos found in printk and Kconfig. Signed-off-by: Masanari Iida <[email protected]> Acked-by: Randy Dunlap <[email protected]> Signed-off-by: Jiri Kosina <[email protected]>
2016-02-15genirq: Use a common macro to go through the actions listDaniel Lezcano5-13/+10
The irq code browses the list of actions differently to inspect the element one by one. Even if it is not a problem, for the sake of consistent code, provide a macro similar to for_each_irq_desc in order to have the same loop to go through the actions list and use it in the code. [ tglx: Renamed the macro ] Signed-off-by: Daniel Lezcano <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]>
2016-02-14Merge 4.5-rc4 into tty-nextGreg Kroah-Hartman9-122/+267
We want the fixes in here, and this resolves a merge error in tty_io.c Signed-off-by: Greg Kroah-Hartman <[email protected]>
2016-02-14Merge branch 'locking-urgent-for-linus' of ↵Linus Torvalds1-6/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull lockdep fix from Thomas Gleixner: "A single fix for the stack trace caching logic in lockdep, where the duplicate avoidance managed to store no back trace at all" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/lockdep: Fix stack trace caching logic
2016-02-13nohz: Implement wide kick on top of irq workFrederic Weisbecker1-8/+4
It simplifies it and allows wide kick to be performed, even when IRQs are disabled, without an asynchronous level in the middle. This comes at a cost of some more overhead on features like perf and posix cpu timers slow-paths, which is probably not much important for nohz full users. Requested-by: Peter Zijlstra <[email protected]> Reviewed-by: Chris Metcalf <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Luiz Capitulino <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Viresh Kumar <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]>
2016-02-13atomic: Export fetch_or()Frederic Weisbecker1-14/+0
Export fetch_or() that's implemented and used internally by the scheduler. We are going to use it for NO_HZ so make it generally available. Reviewed-by: Chris Metcalf <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Luiz Capitulino <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Viresh Kumar <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]>
2016-02-13Merge branch 'linus' into locking/core, to resolve conflictsIngo Molnar6-84/+216
Conflicts: kernel/locking/lockdep.c Signed-off-by: Ingo Molnar <[email protected]>
2016-02-12cgroup: provide cgroup_nov1= to disable controllers in v1 mountsJohannes Weiner1-1/+42
Testing cgroup2 can be painful with system software automatically mounting and populating all cgroup controllers in v1 mode. Sometimes they can be unmounted from rc.local, sometimes even that is too late. Provide a commandline option to disable certain controllers in v1 mounts, so that they remain available for cgroup2 mounts. Example use: cgroup_no_v1=memory,cpu cgroup_no_v1=all Disabling will be confirmed at boot-time as such: [ 0.013770] Disabling cpu control group subsystem in v1 mounts [ 0.016004] Disabling memory control group subsystem in v1 mounts Signed-off-by: Johannes Weiner <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
2016-02-11mm: fix pfn_t vs highmemDan Williams1-1/+1
The pfn_t type uses an unsigned long to store a pfn + flags value. On a 64-bit platform the upper 12 bits of an unsigned long are never used for storing the value of a pfn. However, this is not true on highmem platforms, all 32-bits of a pfn value are used to address a 44-bit physical address space. A pfn_t needs to store a 64-bit value. Link: https://bugzilla.kernel.org/show_bug.cgi?id=112211 Fixes: 01c8f1c44b83 ("mm, dax, gpu: convert vm_insert_mixed to pfn_t") Signed-off-by: Dan Williams <[email protected]> Reported-by: Stuart Foster <[email protected]> Reported-by: Julian Margetson <[email protected]> Tested-by: Julian Margetson <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-02-11kernel/locking/lockdep.c: convert hash tables to hlistsAndrew Morton1-23/+19
Mike said: : CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i. e : kernel with CONFIG_UBSAN_ALIGNMENT fails to load without even any error : message. : : The problem is that ubsan callbacks use spinlocks and might be called : before lockdep is initialized. Particularly this line in the : reserve_ebda_region function causes problem: : : lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); : : If i put lockdep_init() before reserve_ebda_region call in : x86_64_start_reservations kernel loads well. Fix this ordering issue permanently: change lockdep so that it uses hlists for the hash tables. Unlike a list_head, an hlist_head is in its initialized state when it is all-zeroes, so lockdep is ready for operation immediately upon boot - lockdep_init() need not have run. The patch will also save some memory. lockdep_init() and lockdep_initialized can be done away with now - a 4.6 patch has been prepared to do this. Reported-by: Mike Krinkin <[email protected]> Suggested-by: Mike Krinkin <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2016-02-11Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds1-1/+1
Pull networking fixes from David Miller: 1) Fix BPF handling of branch offset adjustmnets on backjumps, from Daniel Borkmann. 2) Make sure selinux knows about SOCK_DESTROY netlink messages, from Lorenzo Colitti. 3) Fix openvswitch tunnel mtu regression, from David Wragg. 4) Fix ICMP handling of TCP sockets in syn_recv state, from Eric Dumazet. 5) Fix SCTP user hmacid byte ordering bug, from Xin Long. 6) Fix recursive locking in ipv6 addrconf, from Subash Abhinov Kasiviswanathan. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: bpf: fix branch offset adjustment on backjumps after patching ctx expansion vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices geneve: Relax MTU constraints vxlan: Relax MTU constraints flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen of: of_mdio: Add marvell, 88e1145 to whitelist of PHY compatibilities. selinux: nlmsgtab: add SOCK_DESTROY to the netlink mapping tables sctp: translate network order to host order when users get a hmacid enic: increment devcmd2 result ring in case of timeout tg3: Fix for tg3 transmit queue 0 timed out when too many gso_segs net:Add sysctl_max_skb_frags tcp: do not drop syn_recv on all icmp reports ipv6: fix a lockdep splat unix: correctly track in-flight fds in sending process user_struct update be2net maintainers' email addresses dwc_eth_qos: Reset hardware before PHY start ipv6: addrconf: Fix recursive spin lock call
2016-02-11PM / suspend: replacing printksaurabh1-3/+3
replacing printk(s) with appropriate pr_info and pr_err in order to fix checkpatch.pl warnings Signed-off-by: Saurabh Sengar <[email protected]> Acked-by: Pavel Machek <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
2016-02-11PM/freezer: y2038, use boottime to compare tstampsAbhilash Jindal1-7/+5
Wall time obtained from do_gettimeofday gives 32 bit timeval which can only represent time until January 2038. This patch moves to ktime_t, a 64-bit time. Also, wall time is susceptible to sudden jumps due to user setting the time or due to NTP. Boot time is constantly increasing time better suited for subtracting two timestamps. Signed-off-by: Abhilash Jindal <[email protected]> Acked-by: Pavel Machek <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
2016-02-11Merge branch 'pm-opp' into pm-cpufreqRafael J. Wysocki3-10/+23
2016-02-10bpf: fix branch offset adjustment on backjumps after patching ctx expansionDaniel Borkmann1-1/+1
When ctx access is used, the kernel often needs to expand/rewrite instructions, so after that patching, branch offsets have to be adjusted for both forward and backward jumps in the new eBPF program, but for backward jumps it fails to account the delta. Meaning, for example, if the expansion happens exactly on the insn that sits at the jump target, it doesn't fix up the back jump offset. Analysis on what the check in adjust_branches() is currently doing: /* adjust offset of jmps if necessary */ if (i < pos && i + insn->off + 1 > pos) insn->off += delta; else if (i > pos && i + insn->off + 1 < pos) insn->off -= delta; First condition (forward jumps): Before: After: insns[0] insns[0] insns[1] <--- i/insn insns[1] <--- i/insn insns[2] <--- pos insns[P] <--- pos insns[3] insns[P] `------| delta insns[4] <--- target_X insns[P] `-----| insns[5] insns[3] insns[4] <--- target_X insns[5] First case is if we cross pos-boundary and the jump instruction was before pos. This is handeled correctly. I.e. if i == pos, then this would mean our jump that we currently check was the patchlet itself that we just injected. Since such patchlets are self-contained and have no awareness of any insns before or after the patched one, the delta is correctly not adjusted. Also, for the second condition in case of i + insn->off + 1 == pos, means we jump to that newly patched instruction, so no offset adjustment are needed. That part is correct. Second condition (backward jumps): Before: After: insns[0] insns[0] insns[1] <--- target_X insns[1] <--- target_X insns[2] <--- pos <-- target_Y insns[P] <--- pos <-- target_Y insns[3] insns[P] `------| delta insns[4] <--- i/insn insns[P] `-----| insns[5] insns[3] insns[4] <--- i/insn insns[5] Second interesting case is where we cross pos-boundary and the jump instruction was after pos. Backward jump with i == pos would be impossible and pose a bug somewhere in the patchlet, so the first condition checking i > pos is okay only by itself. However, i + insn->off + 1 < pos does not always work as intended to trigger the adjustment. It works when jump targets would be far off where the delta wouldn't matter. But, for example, where the fixed insn->off before pointed to pos (target_Y), it now points to pos + delta, so that additional room needs to be taken into account for the check. This means that i) both tests here need to be adjusted into pos + delta, and ii) for the second condition, the test needs to be <= as pos itself can be a target in the backjump, too. Fixes: 9bac3d6d548e ("bpf: allow extended BPF programs access skb fields") Signed-off-by: Daniel Borkmann <[email protected]> Signed-off-by: David S. Miller <[email protected]>
2016-02-10Merge branch 'for-4.5-fixes' of ↵Linus Torvalds2-30/+72
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup fixes from Tejun Heo: - The destruction path of cgroup objects are asynchronous and multi-staged and some of them ended up destroying parents before children leading to failures in cpu and memory controllers. Ensure that parents are always destroyed after children. - cpuset mm node migration was performed synchronously while holding threadgroup and cgroup mutexes and the recent threadgroup locking update resulted in a possible deadlock. The migration is best effort and shouldn't have been performed under those locks to begin with. Made asynchronous. - Minor documentation fix. * 'for-4.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: Documentation: cgroup: Fix 'cgroup-legacy' -> 'cgroup-v1' cgroup: make sure a parent css isn't freed before its children cgroup: make sure a parent css isn't offlined before its children cpuset: make mm migration asynchronous
2016-02-10Merge branch 'for-4.5-fixes' of ↵Linus Torvalds1-7/+67
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fixes from Tejun Heo: "Workqueue fixes for v4.5-rc3. - Remove a spurious triggering of flush dependency warning. - Officially break local execution guarantee of unbound work items and add a debug feature to flush out usages which depend on it. - Work around CPU -> NODE mapping becoming invalid on CPU offline. The branch is young but pushing out early as stable kernels are being affected" * 'for-4.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookup workqueue: implement "workqueue.debug_force_rr_cpu" debug feature workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs Revert "workqueue: make sure delayed work run in local cpu" workqueue: skip flush dependency checks for legacy workqueues
2016-02-10workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookupTejun Heo1-0/+10
When looking up the pool_workqueue to use for an unbound workqueue, workqueue assumes that the target CPU is always bound to a valid NUMA node. However, currently, when a CPU goes offline, the mapping is destroyed and cpu_to_node() returns NUMA_NO_NODE. This has always been broken but hasn't triggered often enough before 874bbfe600a6 ("workqueue: make sure delayed work run in local cpu"). After the commit, workqueue forcifully assigns the local CPU for delayed work items without explicit target CPU to fix a different issue. This widens the window where CPU can go offline while a delayed work item is pending causing delayed work items dispatched with target CPU set to an already offlined CPU. The resulting NUMA_NO_NODE mapping makes workqueue try to queue the work item on a NULL pool_workqueue and thus crash. While 874bbfe600a6 has been reverted for a different reason making the bug less visible again, it can still happen. Fix it by mapping NUMA_NO_NODE to the default pool_workqueue from unbound_pwq_by_node(). This is a temporary workaround. The long term solution is keeping CPU -> NODE mapping stable across CPU off/online cycles which is being worked on. Signed-off-by: Tejun Heo <[email protected]> Reported-by: Mike Galbraith <[email protected]> Cc: Tang Chen <[email protected]> Cc: Rafael J. Wysocki <[email protected]> Cc: Len Brown <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/g/[email protected] Link: http://lkml.kernel.org/g/[email protected]
2016-02-09Merge tag 'fixes-for-linus' of ↵Linus Torvalds1-45/+75
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module fixes from Rusty Russell: "Fix for async_probe module param added in 4.3 (clearly not widely used yet), and a much more interesting kallsyms race which has been around approximately forever. This fix is more invasive, and will require some care in backporting, but I hated all the bandaids I could think of, so... There are some more coming, which are only for breakages introduced this cycle (livepatch), but wanted these in now" * tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: modules: fix longstanding /proc/kallsyms vs module insertion race. module: wrapper for symbol name. modules: fix modparam async_probe request
2016-02-09workqueue: implement "workqueue.debug_force_rr_cpu" debug featureTejun Heo1-2/+21
Workqueue used to guarantee local execution for work items queued without explicit target CPU. The guarantee is gone now which can break some usages in subtle ways. To flush out those cases, this patch implements a debug feature which forces round-robin CPU selection for all such work items. The debug feature defaults to off and can be enabled with a kernel parameter. The default can be flipped with a debug config option. If you hit this commit during bisection, please refer to 041bd12e272c ("Revert "workqueue: make sure delayed work run in local cpu"") for more information and ping me. Signed-off-by: Tejun Heo <[email protected]>
2016-02-09workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUsMike Galbraith1-2/+32
WORK_CPU_UNBOUND work items queued to a bound workqueue always run locally. This is a good thing normally, but not when the user has asked us to keep unbound work away from certain CPUs. Round robin these to wq_unbound_cpumask CPUs instead, as perturbation avoidance trumps performance. tj: Cosmetic and comment changes. WARN_ON_ONCE() dropped from empty (wq_unbound_cpumask AND cpu_online_mask). If we want that, it should be done when config changes. Signed-off-by: Mike Galbraith <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
2016-02-09Revert "workqueue: make sure delayed work run in local cpu"Tejun Heo1-4/+4
This reverts commit 874bbfe600a660cba9c776b3957b1ce393151b76. Workqueue used to implicity guarantee that work items queued without explicit CPU specified are put on the local CPU. Recent changes in timer broke the guarantee and led to vmstat breakage which was fixed by 176bed1de5bf ("vmstat: explicitly schedule per-cpu work on the CPU we need it to run on"). vmstat is the most likely to expose the issue and it's quite possible that there are other similar problems which are a lot more difficult to trigger. As a preventive measure, 874bbfe600a6 ("workqueue: make sure delayed work run in local cpu") was applied to restore the local CPU guarnatee. Unfortunately, the change exposed a bug in timer code which got fixed by 22b886dd1018 ("timers: Use proper base migration in add_timer_on()"). Due to code restructuring, the commit couldn't be backported beyond certain point and stable kernels which only had 874bbfe600a6 started crashing. The local CPU guarantee was accidental more than anything else and we want to get rid of it anyway. As, with the vmstat case fixed, 874bbfe600a6 is causing more problems than it's fixing, it has been decided to take the chance and officially break the guarantee by reverting the commit. A debug feature will be added to force foreign CPU assignment to expose cases relying on the guarantee and fixes for the individual cases will be backported to stable as necessary. Signed-off-by: Tejun Heo <[email protected]> Fixes: 874bbfe600a6 ("workqueue: make sure delayed work run in local cpu") Link: http://lkml.kernel.org/g/[email protected] Cc: [email protected] Cc: Mike Galbraith <[email protected]> Cc: Henrique de Moraes Holschuh <[email protected]> Cc: Daniel Bilik <[email protected]> Cc: Jan Kara <[email protected]> Cc: Shaohua Li <[email protected]> Cc: Sasha Levin <[email protected]> Cc: Ben Hutchings <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Daniel Bilik <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Michal Hocko <[email protected]>
2016-02-09sched/numa: Spread memory according to CPU and memory useRik van Riel1-40/+47
The pseudo-interleaving in NUMA placement has a fundamental problem: using hard usage thresholds to spread memory equally between nodes can prevent workloads from converging, or keep memory "trapped" on nodes where the workload is barely running any more. In order for workloads to properly converge, the memory migration should not be stopped when nodes reach parity, but instead be distributed according to how heavily memory is used from each node. This way memory migration and task migration reinforce each other, instead of one putting the brakes on the other. Remove the hard thresholds from the pseudo-interleaving code, and instead use a more gradual policy on memory placement. This also seems to improve convergence of workloads that do not run flat out, but sleep in between bursts of activity. We still want to slow down NUMA scanning and migration once a workload has settled on a few actively used nodes, so keep the 3/4 hysteresis in place. Keep track of whether a workload is actively running on multiple nodes, so task_numa_migrate does a full scan of the system for better task placement. In the case of running 3 SPECjbb2005 instances on a 4 node system, this code seems to result in fairer distribution of memory between nodes, with more memory bandwidth for each instance. Signed-off-by: Rik van Riel <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] [ Minor readability tweaks. ] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-09locking/lockdep: Eliminate lockdep_init()Andrey Ryabinin1-59/+0
Lockdep is initialized at compile time now. Get rid of lockdep_init(). Signed-off-by: Andrey Ryabinin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Krinkin <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-09locking/lockdep: Convert hash tables to hlistsAndrew Morton1-23/+19
Mike said: : CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i.e. : kernel with CONFIG_UBSAN_ALIGNMENT=y fails to load without even any error : message. : : The problem is that ubsan callbacks use spinlocks and might be called : before lockdep is initialized. Particularly this line in the : reserve_ebda_region function causes problem: : : lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); : : If i put lockdep_init() before reserve_ebda_region call in : x86_64_start_reservations kernel loads well. Fix this ordering issue permanently: change lockdep so that it uses hlists for the hash tables. Unlike a list_head, an hlist_head is in its initialized state when it is all-zeroes, so lockdep is ready for operation immediately upon boot - lockdep_init() need not have run. The patch will also save some memory. Probably lockdep_init() and lockdep_initialized can be done away with now. Suggested-by: Mike Krinkin <[email protected]> Reported-by: Mike Krinkin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-09sched/debug: Make schedstats a runtime tunable that is disabled by defaultMel Gorman8-90/+232
schedstats is very useful during debugging and performance tuning but it incurs overhead to calculate the stats. As such, even though it can be disabled at build time, it is often enabled as the information is useful. This patch adds a kernel command-line and sysctl tunable to enable or disable schedstats on demand (when it's built in). It is disabled by default as someone who knows they need it can also learn to enable it when necessary. The benefits are dependent on how scheduler-intensive the workload is. If it is then the patch reduces the number of cycles spent calculating the stats with a small benefit from reducing the cache footprint of the scheduler. These measurements were taken from a 48-core 2-socket machine with Xeon(R) E5-2670 v3 cpus although they were also tested on a single socket machine 8-core machine with Intel i7-3770 processors. netperf-tcp 4.5.0-rc1 4.5.0-rc1 vanilla nostats-v3r1 Hmean 64 560.45 ( 0.00%) 575.98 ( 2.77%) Hmean 128 766.66 ( 0.00%) 795.79 ( 3.80%) Hmean 256 950.51 ( 0.00%) 981.50 ( 3.26%) Hmean 1024 1433.25 ( 0.00%) 1466.51 ( 2.32%) Hmean 2048 2810.54 ( 0.00%) 2879.75 ( 2.46%) Hmean 3312 4618.18 ( 0.00%) 4682.09 ( 1.38%) Hmean 4096 5306.42 ( 0.00%) 5346.39 ( 0.75%) Hmean 8192 10581.44 ( 0.00%) 10698.15 ( 1.10%) Hmean 16384 18857.70 ( 0.00%) 18937.61 ( 0.42%) Small gains here, UDP_STREAM showed nothing intresting and neither did the TCP_RR tests. The gains on the 8-core machine were very similar. tbench4 4.5.0-rc1 4.5.0-rc1 vanilla nostats-v3r1 Hmean mb/sec-1 500.85 ( 0.00%) 522.43 ( 4.31%) Hmean mb/sec-2 984.66 ( 0.00%) 1018.19 ( 3.41%) Hmean mb/sec-4 1827.91 ( 0.00%) 1847.78 ( 1.09%) Hmean mb/sec-8 3561.36 ( 0.00%) 3611.28 ( 1.40%) Hmean mb/sec-16 5824.52 ( 0.00%) 5929.03 ( 1.79%) Hmean mb/sec-32 10943.10 ( 0.00%) 10802.83 ( -1.28%) Hmean mb/sec-64 15950.81 ( 0.00%) 16211.31 ( 1.63%) Hmean mb/sec-128 15302.17 ( 0.00%) 15445.11 ( 0.93%) Hmean mb/sec-256 14866.18 ( 0.00%) 15088.73 ( 1.50%) Hmean mb/sec-512 15223.31 ( 0.00%) 15373.69 ( 0.99%) Hmean mb/sec-1024 14574.25 ( 0.00%) 14598.02 ( 0.16%) Hmean mb/sec-2048 13569.02 ( 0.00%) 13733.86 ( 1.21%) Hmean mb/sec-3072 12865.98 ( 0.00%) 13209.23 ( 2.67%) Small gains of 2-4% at low thread counts and otherwise flat. The gains on the 8-core machine were slightly different tbench4 on 8-core i7-3770 single socket machine Hmean mb/sec-1 442.59 ( 0.00%) 448.73 ( 1.39%) Hmean mb/sec-2 796.68 ( 0.00%) 794.39 ( -0.29%) Hmean mb/sec-4 1322.52 ( 0.00%) 1343.66 ( 1.60%) Hmean mb/sec-8 2611.65 ( 0.00%) 2694.86 ( 3.19%) Hmean mb/sec-16 2537.07 ( 0.00%) 2609.34 ( 2.85%) Hmean mb/sec-32 2506.02 ( 0.00%) 2578.18 ( 2.88%) Hmean mb/sec-64 2511.06 ( 0.00%) 2569.16 ( 2.31%) Hmean mb/sec-128 2313.38 ( 0.00%) 2395.50 ( 3.55%) Hmean mb/sec-256 2110.04 ( 0.00%) 2177.45 ( 3.19%) Hmean mb/sec-512 2072.51 ( 0.00%) 2053.97 ( -0.89%) In constract, this shows a relatively steady 2-3% gain at higher thread counts. Due to the nature of the patch and the type of workload, it's not a surprise that the result will depend on the CPU used. hackbench-pipes 4.5.0-rc1 4.5.0-rc1 vanilla nostats-v3r1 Amean 1 0.0637 ( 0.00%) 0.0660 ( -3.59%) Amean 4 0.1229 ( 0.00%) 0.1181 ( 3.84%) Amean 7 0.1921 ( 0.00%) 0.1911 ( 0.52%) Amean 12 0.3117 ( 0.00%) 0.2923 ( 6.23%) Amean 21 0.4050 ( 0.00%) 0.3899 ( 3.74%) Amean 30 0.4586 ( 0.00%) 0.4433 ( 3.33%) Amean 48 0.5910 ( 0.00%) 0.5694 ( 3.65%) Amean 79 0.8663 ( 0.00%) 0.8626 ( 0.43%) Amean 110 1.1543 ( 0.00%) 1.1517 ( 0.22%) Amean 141 1.4457 ( 0.00%) 1.4290 ( 1.16%) Amean 172 1.7090 ( 0.00%) 1.6924 ( 0.97%) Amean 192 1.9126 ( 0.00%) 1.9089 ( 0.19%) Some small gains and losses and while the variance data is not included, it's close to the noise. The UMA machine did not show anything particularly different pipetest 4.5.0-rc1 4.5.0-rc1 vanilla nostats-v2r2 Min Time 4.13 ( 0.00%) 3.99 ( 3.39%) 1st-qrtle Time 4.38 ( 0.00%) 4.27 ( 2.51%) 2nd-qrtle Time 4.46 ( 0.00%) 4.39 ( 1.57%) 3rd-qrtle Time 4.56 ( 0.00%) 4.51 ( 1.10%) Max-90% Time 4.67 ( 0.00%) 4.60 ( 1.50%) Max-93% Time 4.71 ( 0.00%) 4.65 ( 1.27%) Max-95% Time 4.74 ( 0.00%) 4.71 ( 0.63%) Max-99% Time 4.88 ( 0.00%) 4.79 ( 1.84%) Max Time 4.93 ( 0.00%) 4.83 ( 2.03%) Mean Time 4.48 ( 0.00%) 4.39 ( 1.91%) Best99%Mean Time 4.47 ( 0.00%) 4.39 ( 1.91%) Best95%Mean Time 4.46 ( 0.00%) 4.38 ( 1.93%) Best90%Mean Time 4.45 ( 0.00%) 4.36 ( 1.98%) Best50%Mean Time 4.36 ( 0.00%) 4.25 ( 2.49%) Best10%Mean Time 4.23 ( 0.00%) 4.10 ( 3.13%) Best5%Mean Time 4.19 ( 0.00%) 4.06 ( 3.20%) Best1%Mean Time 4.13 ( 0.00%) 4.00 ( 3.39%) Small improvement and similar gains were seen on the UMA machine. The gain is small but it stands to reason that doing less work in the scheduler is a good thing. The downside is that the lack of schedstats and tracepoints may be surprising to experts doing performance analysis until they find the existence of the schedstats= parameter or schedstats sysctl. It will be automatically activated for latencytop and sleep profiling to alleviate the problem. For tracepoints, there is a simple warning as it's not safe to activate schedstats in the context when it's known the tracepoint may be wanted but is unavailable. Signed-off-by: Mel Gorman <[email protected]> Reviewed-by: Matt Fleming <[email protected]> Reviewed-by: Srikar Dronamraju <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-09kprobes: Optimize hot path by using percpu counter to collect 'nhit' statisticsMartin KaFai Lau1-4/+15
When doing ebpf+kprobe on some hot TCP functions (e.g. tcp_rcv_established), the kprobe_dispatcher() function shows up in 'perf report'. In kprobe_dispatcher(), there is a lot of cache bouncing on 'tk->nhit++'. 'tk->nhit' and 'tk->tp.flags' also share the same cacheline. perf report (cycles:pp): 8.30% ipv4_dst_check 4.74% copy_user_enhanced_fast_string 3.93% dst_release 2.80% tcp_v4_rcv 2.31% queued_spin_lock_slowpath 2.30% _raw_spin_lock 1.88% mlx4_en_process_rx_cq 1.84% eth_get_headlen 1.81% ip_rcv_finish ~~~~ 1.71% kprobe_dispatcher ~~~~ 1.55% mlx4_en_xmit 1.09% __probe_kernel_read perf report after patch: 9.15% ipv4_dst_check 5.00% copy_user_enhanced_fast_string 4.12% dst_release 2.96% tcp_v4_rcv 2.50% _raw_spin_lock 2.39% queued_spin_lock_slowpath 2.11% eth_get_headlen 2.03% mlx4_en_process_rx_cq 1.69% mlx4_en_xmit 1.19% ip_rcv_finish 1.12% __probe_kernel_read 1.02% ehci_hcd_cleanup Signed-off-by: Martin KaFai Lau <[email protected]> Acked-by: Masami Hiramatsu <[email protected]> Acked-by: Steven Rostedt <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Josef Bacik <[email protected]> Cc: Kernel Team <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-09locking/lockdep: Fix stack trace caching logicDmitry Vyukov1-6/+10
check_prev_add() caches saved stack trace in static trace variable to avoid duplicate save_trace() calls in dependencies involving trylocks. But that caching logic contains a bug. We may not save trace on first iteration due to early return from check_prev_add(). Then on the second iteration when we actually need the trace we don't save it because we think that we've already saved it. Let check_prev_add() itself control when stack is saved. There is another bug. Trace variable is protected by graph lock. But we can temporary release graph lock during printing. Fix this by invalidating cached stack trace when we release graph lock. Signed-off-by: Dmitry Vyukov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2016-02-08audit: Fix typo in commentWei Yuan2-4/+4
Signed-off-by: Weiyuan <[email protected]> Signed-off-by: Paul Moore <[email protected]>
2016-02-08genirq: Add default affinity mask command line optionThomas Gleixner1-2/+19
If we isolate CPUs, then we don't want random device interrupts on them. Even w/o the user space irq balancer enabled we can end up with irqs on non boot cpus and chasing newly requested interrupts is a tedious task. Allow to restrict the default irq affinity mask. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Sebastian Siewior <[email protected]> Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1602031948190.25254@nanos Signed-off-by: Thomas Gleixner <[email protected]>
2016-02-06bpf: add lookup/update support for per-cpu hash and array mapsAlexei Starovoitov3-26/+178
The functions bpf_map_lookup_elem(map, key, value) and bpf_map_update_elem(map, key, value, flags) need to get/set values from all-cpus for per-cpu hash and array maps, so that user space can aggregate/update them as necessary. Example of single counter aggregation in user space: unsigned int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); long values[nr_cpus]; long value = 0; bpf_lookup_elem(fd, key, values); for (i = 0; i < nr_cpus; i++) value += values[i]; The user space must provide round_up(value_size, 8) * nr_cpus array to get/set values, since kernel will use 'long' copy of per-cpu values to try to copy good counters atomically. It's a best-effort, since bpf programs and user space are racing to access the same memory. Signed-off-by: Alexei Starovoitov <[email protected]> Signed-off-by: David S. Miller <[email protected]>
2016-02-06bpf: introduce BPF_MAP_TYPE_PERCPU_ARRAY mapAlexei Starovoitov1-11/+91
Primary use case is a histogram array of latency where bpf program computes the latency of block requests or other events and stores histogram of latency into array of 64 elements. All cpus are constantly running, so normal increment is not accurate, bpf_xadd causes cache ping-pong and this per-cpu approach allows fastest collision-free counters. Signed-off-by: Alexei Starovoitov <[email protected]> Signed-off-by: David S. Miller <[email protected]>
2016-02-06bpf: introduce BPF_MAP_TYPE_PERCPU_HASH mapAlexei Starovoitov1-47/+228
Introduce BPF_MAP_TYPE_PERCPU_HASH map type which is used to do accurate counters without need to use BPF_XADD instruction which turned out to be too costly for high-performance network monitoring. In the typical use case the 'key' is the flow tuple or other long living object that sees a lot of events per second. bpf_map_lookup_elem() returns per-cpu area. Example: struct { u32 packets; u32 bytes; } * ptr = bpf_map_lookup_elem(&map, &key); /* ptr points to this_cpu area of the value, so the following * increments will not collide with other cpus */ ptr->packets ++; ptr->bytes += skb->len; bpf_update_elem() atomically creates a new element where all per-cpu values are zero initialized and this_cpu value is populated with given 'value'. Note that non-per-cpu hash map always allocates new element and then deletes old after rcu grace period to maintain atomicity of update. Per-cpu hash map updates element values in-place. Signed-off-by: Alexei Starovoitov <[email protected]> Signed-off-by: David S. Miller <[email protected]>