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* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds2018-06-071-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull networking updates from David Miller: 1) Add Maglev hashing scheduler to IPVS, from Inju Song. 2) Lots of new TC subsystem tests from Roman Mashak. 3) Add TCP zero copy receive and fix delayed acks and autotuning with SO_RCVLOWAT, from Eric Dumazet. 4) Add XDP_REDIRECT support to mlx5 driver, from Jesper Dangaard Brouer. 5) Add ttl inherit support to vxlan, from Hangbin Liu. 6) Properly separate ipv6 routes into their logically independant components. fib6_info for the routing table, and fib6_nh for sets of nexthops, which thus can be shared. From David Ahern. 7) Add bpf_xdp_adjust_tail helper, which can be used to generate ICMP messages from XDP programs. From Nikita V. Shirokov. 8) Lots of long overdue cleanups to the r8169 driver, from Heiner Kallweit. 9) Add BTF ("BPF Type Format"), from Martin KaFai Lau. 10) Add traffic condition monitoring to iwlwifi, from Luca Coelho. 11) Plumb extack down into fib_rules, from Roopa Prabhu. 12) Add Flower classifier offload support to igb, from Vinicius Costa Gomes. 13) Add UDP GSO support, from Willem de Bruijn. 14) Add documentation for eBPF helpers, from Quentin Monnet. 15) Add TLS tx offload to mlx5, from Ilya Lesokhin. 16) Allow applications to be given the number of bytes available to read on a socket via a control message returned from recvmsg(), from Soheil Hassas Yeganeh. 17) Add x86_32 eBPF JIT compiler, from Wang YanQing. 18) Add AF_XDP sockets, with zerocopy support infrastructure as well. From Björn Töpel. 19) Remove indirect load support from all of the BPF JITs and handle these operations in the verifier by translating them into native BPF instead. From Daniel Borkmann. 20) Add GRO support to ipv6 gre tunnels, from Eran Ben Elisha. 21) Allow XDP programs to do lookups in the main kernel routing tables for forwarding. From David Ahern. 22) Allow drivers to store hardware state into an ELF section of kernel dump vmcore files, and use it in cxgb4. From Rahul Lakkireddy. 23) Various RACK and loss detection improvements in TCP, from Yuchung Cheng. 24) Add TCP SACK compression, from Eric Dumazet. 25) Add User Mode Helper support and basic bpfilter infrastructure, from Alexei Starovoitov. 26) Support ports and protocol values in RTM_GETROUTE, from Roopa Prabhu. 27) Support bulking in ->ndo_xdp_xmit() API, from Jesper Dangaard Brouer. 28) Add lots of forwarding selftests, from Petr Machata. 29) Add generic network device failover driver, from Sridhar Samudrala. * ra.kernel.org:/pub/scm/linux/kernel/git/davem/net-next: (1959 commits) strparser: Add __strp_unpause and use it in ktls. rxrpc: Fix terminal retransmission connection ID to include the channel net: hns3: Optimize PF CMDQ interrupt switching process net: hns3: Fix for VF mailbox receiving unknown message net: hns3: Fix for VF mailbox cannot receiving PF response bnx2x: use the right constant Revert "net: sched: cls: Fix offloading when ingress dev is vxlan" net: dsa: b53: Fix for brcm tag issue in Cygnus SoC enic: fix UDP rss bits netdev-FAQ: clarify DaveM's position for stable backports rtnetlink: validate attributes in do_setlink() mlxsw: Add extack messages for port_{un, }split failures netdevsim: Add extack error message for devlink reload devlink: Add extack to reload and port_{un, }split operations net: metrics: add proper netlink validation ipmr: fix error path when ipmr_new_table fails ip6mr: only set ip6mr_table from setsockopt when ip6mr_new_table succeeds net: hns3: remove unused hclgevf_cfg_func_mta_filter netfilter: provide udp*_lib_lookup for nf_tproxy qed*: Utilize FW 8.37.2.0 ...
| * bpf, x86_32: add eBPF JIT compiler for ia32Wang YanQing2018-05-031-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The JIT compiler emits ia32 bit instructions. Currently, It supports eBPF only. Classic BPF is supported because of the conversion by BPF core. Almost all instructions from eBPF ISA supported except the following: BPF_ALU64 | BPF_DIV | BPF_K BPF_ALU64 | BPF_DIV | BPF_X BPF_ALU64 | BPF_MOD | BPF_K BPF_ALU64 | BPF_MOD | BPF_X BPF_STX | BPF_XADD | BPF_W BPF_STX | BPF_XADD | BPF_DW It doesn't support BPF_JMP|BPF_CALL with BPF_PSEUDO_CALL at the moment. IA32 has few general purpose registers, EAX|EDX|ECX|EBX|ESI|EDI. I use EAX|EDX|ECX|EBX as temporary registers to simulate instructions in eBPF ISA, and allocate ESI|EDI to BPF_REG_AX for constant blinding, all others eBPF registers, R0-R10, are simulated through scratch space on stack. The reasons behind the hardware registers allocation policy are: 1:MUL need EAX:EDX, shift operation need ECX, so they aren't fit for general eBPF 64bit register simulation. 2:We need at least 4 registers to simulate most eBPF ISA operations on registers operands instead of on register&memory operands. 3:We need to put BPF_REG_AX on hardware registers, or constant blinding will degrade jit performance heavily. Tested on PC (Intel(R) Core(TM) i5-5200U CPU). Testing results on i5-5200U: 1) test_bpf: Summary: 349 PASSED, 0 FAILED, [319/341 JIT'ed] 2) test_progs: Summary: 83 PASSED, 0 FAILED. 3) test_lpm: OK 4) test_lru_map: OK 5) test_verifier: Summary: 828 PASSED, 0 FAILED. Above tests are all done in following two conditions separately: 1:bpf_jit_enable=1 and bpf_jit_harden=0 2:bpf_jit_enable=1 and bpf_jit_harden=2 Below are some numbers for this jit implementation: Note: I run test_progs in kselftest 100 times continuously for every condition, the numbers are in format: total/times=avg. The numbers that test_bpf reports show almost the same relation. a:jit_enable=0 and jit_harden=0 b:jit_enable=1 and jit_harden=0 test_pkt_access:PASS:ipv4:15622/100=156 test_pkt_access:PASS:ipv4:10674/100=106 test_pkt_access:PASS:ipv6:9130/100=91 test_pkt_access:PASS:ipv6:4855/100=48 test_xdp:PASS:ipv4:240198/100=2401 test_xdp:PASS:ipv4:138912/100=1389 test_xdp:PASS:ipv6:137326/100=1373 test_xdp:PASS:ipv6:68542/100=685 test_l4lb:PASS:ipv4:61100/100=611 test_l4lb:PASS:ipv4:37302/100=373 test_l4lb:PASS:ipv6:101000/100=1010 test_l4lb:PASS:ipv6:55030/100=550 c:jit_enable=1 and jit_harden=2 test_pkt_access:PASS:ipv4:10558/100=105 test_pkt_access:PASS:ipv6:5092/100=50 test_xdp:PASS:ipv4:131902/100=1319 test_xdp:PASS:ipv6:77932/100=779 test_l4lb:PASS:ipv4:38924/100=389 test_l4lb:PASS:ipv6:57520/100=575 The numbers show we get 30%~50% improvement. See Documentation/networking/filter.txt for more information. Changelog: Changes v5-v6: 1:Add do {} while (0) to RETPOLINE_RAX_BPF_JIT for consistence reason. 2:Clean up non-standard comments, reported by Daniel Borkmann. 3:Fix a memory leak issue, repoted by Daniel Borkmann. Changes v4-v5: 1:Delete is_on_stack, BPF_REG_AX is the only one on real hardware registers, so just check with it. 2:Apply commit 1612a981b766 ("bpf, x64: fix JIT emission for dead code"), suggested by Daniel Borkmann. Changes v3-v4: 1:Fix changelog in commit. I install llvm-6.0, then test_progs willn't report errors. I submit another patch: "bpf: fix misaligned access for BPF_PROG_TYPE_PERF_EVENT program type on x86_32 platform" to fix another problem, after that patch, test_verifier willn't report errors too. 2:Fix clear r0[1] twice unnecessarily in *BPF_IND|BPF_ABS* simulation. Changes v2-v3: 1:Move BPF_REG_AX to real hardware registers for performance reason. 3:Using bpf_load_pointer instead of bpf_jit32.S, suggested by Daniel Borkmann. 4:Delete partial codes in 1c2a088a6626, suggested by Daniel Borkmann. 5:Some bug fixes and comments improvement. Changes v1-v2: 1:Fix bug in emit_ia32_neg64. 2:Fix bug in emit_ia32_arsh_r64. 3:Delete filename in top level comment, suggested by Thomas Gleixner. 4:Delete unnecessary boiler plate text, suggested by Thomas Gleixner. 5:Rewrite some words in changelog. 6:CodingSytle improvement and a little more comments. Signed-off-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
* | docs/admin-guide/mm: start moving here files from Documentation/vmMike Rapoport2018-04-281-2/+2
| | | | | | | | | | | | | | | | | | | | Several documents in Documentation/vm fit quite well into the "admin/user guide" category. The documents that don't overload the reader with lots of implementation details and provide coherent description of certain feature can be moved to Documentation/admin-guide/mm. Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | Merge branch 'mm-rst' into docs-nextJonathan Corbet2018-04-161-3/+3
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mike Rapoport says: These patches convert files in Documentation/vm to ReST format, add an initial index and link it to the top level documentation. There are no contents changes in the documentation, except few spelling fixes. The relatively large diffstat stems from the indentation and paragraph wrapping changes. I've tried to keep the formatting as consistent as possible, but I could miss some places that needed markup and add some markup where it was not necessary. [jc: significant conflicts in vm/hmm.rst]
| * docs/vm: rename documentation files to .rstMike Rapoport2018-04-161-3/+3
| | | | | | | | | | Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | taint: add taint for randstructKees Cook2018-04-111-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the randstruct plugin can intentionally produce extremely unusual kernel structure layouts (even performance pathological ones), some maintainers want to be able to trivially determine if an Oops is coming from a randstruct-built kernel, so as to keep their sanity when debugging. This adds the new flag and initializes taint_mask immediately when built with randstruct. Link: http://lkml.kernel.org/r/1519084390-43867-4-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | taint: consolidate documentationKees Cook2018-04-111-26/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This consolidates the taint bit documentation into a single place with both numeric and letter values. Additionally adds the missing TAINT_AUX documentation. Link: http://lkml.kernel.org/r/1519084390-43867-3-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE requestJoonsoo Kim2018-04-111-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Freepage on ZONE_HIGHMEM doesn't work for kernel memory so it's not that important to reserve. When ZONE_MOVABLE is used, this problem would theorectically cause to decrease usable memory for GFP_HIGHUSER_MOVABLE allocation request which is mainly used for page cache and anon page allocation. So, fix it by setting 0 to sysctl_lowmem_reserve_ratio[ZONE_HIGHMEM]. And, defining sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES - 1 size makes code complex. For example, if there is highmem system, following reserve ratio is activated for *NORMAL ZONE* which would be easyily misleading people. #ifdef CONFIG_HIGHMEM 32 #endif This patch also fixes this situation by defining sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES and place "#ifdef" to right place. Link: http://lkml.kernel.org/r/1504672525-17915-1-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Tony Lindgren <tony@atomide.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Laura Abbott <lauraa@codeaurora.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Cc: <linux-api@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | net: do not create fallback tunnels for non-default namespacesEric Dumazet2018-03-091-0/+12
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | fallback tunnels (like tunl0, gre0, gretap0, erspan0, sit0, ip6tnl0, ip6gre0) are automatically created when the corresponding module is loaded. These tunnels are also automatically created when a new network namespace is created, at a great cost. In many cases, netns are used for isolation purposes, and these extra network devices are a waste of resources. We are using thousands of netns per host, and hit the netns creation/delete bottleneck a lot. (Many thanks to Kirill for recent work on this) Add a new sysctl so that we can opt-out from this automatic creation. Note that these tunnels are still created for the initial namespace, to be the least intrusive for typical setups. Tested: lpk43:~# cat add_del_unshare.sh for i in `seq 1 40` do (for j in `seq 1 100` ; do unshare -n /bin/true >/dev/null ; done) & done wait lpk43:~# echo 0 >/proc/sys/net/core/fb_tunnels_only_for_init_net lpk43:~# time ./add_del_unshare.sh real 0m37.521s user 0m0.886s sys 7m7.084s lpk43:~# echo 1 >/proc/sys/net/core/fb_tunnels_only_for_init_net lpk43:~# time ./add_del_unshare.sh real 0m4.761s user 0m0.851s sys 1m8.343s lpk43:~# Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Documentation/sysctl/user.txt: fix typoKangmin Park2018-02-071-1/+1
| | | | | | | | | | | Fix 'documetation' to 'documentation' Link: http://lkml.kernel.org/r/CAKW4uUxRPZz59aWAX8ytaCB5=Qh6d_CvAnO7rYq-6NRAnQJbDA@mail.gmail.com Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jiri Kosina <trivial@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'docs-4.16' of git://git.lwn.net/linuxLinus Torvalds2018-02-011-1/+16
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation updates from Jonathan Corbet: "Documentation updates for 4.16. New stuff includes refcount_t documentation, errseq documentation, kernel-doc support for nested structure definitions, the removal of lots of crufty kernel-doc support for unused formats, SPDX tag documentation, the beginnings of a manual for subsystem maintainers, and lots of fixes and updates. As usual, some of the changesets reach outside of Documentation/ to effect kerneldoc comment fixes. It also adds the new LICENSES directory, of which Thomas promises I do not need to be the maintainer" * tag 'docs-4.16' of git://git.lwn.net/linux: (65 commits) linux-next: docs-rst: Fix typos in kfigure.py linux-next: DOC: HWPOISON: Fix path to debugfs in hwpoison.txt Documentation: Fix misconversion of #if docs: add index entry for networking/msg_zerocopy Documentation: security/credentials.rst: explain need to sort group_list LICENSES: Add MPL-1.1 license LICENSES: Add the GPL 1.0 license LICENSES: Add Linux syscall note exception LICENSES: Add the MIT license LICENSES: Add the BSD-3-clause "Clear" license LICENSES: Add the BSD 3-clause "New" or "Revised" License LICENSES: Add the BSD 2-clause "Simplified" license LICENSES: Add the LGPL-2.1 license LICENSES: Add the LGPL 2.0 license LICENSES: Add the GPL 2.0 license Documentation: Add license-rules.rst to describe how to properly identify file licenses scripts: kernel_doc: better handle show warnings logic fs/*/Kconfig: drop links to 404-compliant http://acl.bestbits.at doc: md: Fix a file name to md-fault.c in fault-injection.txt errseq: Add to documentation tree ...
| * doc: update kptr_restrict documentationTobin C. Harding2017-12-211-1/+2
| | | | | | | | | | | | | | | | | | | | Recently the behaviour of printk specifier %pK was changed. The documentation does not currently mirror this. Update documentation for sysctl kptr_restrict. Signed-off-by: Tobin C. Harding <me@tobin.cc> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
| * Documentation: Better document the hardlockup_panic sysctlScott Wood2017-12-111-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | Commit ac1f591249d95372f ("kernel/watchdog.c: add sysctl knob hardlockup_panic") added the hardlockup_panic sysctl, but did not add it to Documentation/sysctl/kernel.txt. Add this, and reference it from the corresponding entry in Documentation/admin-guide/kernel-parameters.txt. Signed-off-by: Scott Wood <swood@redhat.com> Acked-by: Christoph von Recklinghausen <crecklin@redhat.com> Acked-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | Merge branch 'akpm' (patches from Andrew)Linus Torvalds2018-02-011-25/+0
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge updates from Andrew Morton: - misc fixes - ocfs2 updates - most of MM * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (118 commits) mm: remove PG_highmem description tools, vm: new option to specify kpageflags file mm/swap.c: make functions and their kernel-doc agree mm, memory_hotplug: fix memmap initialization mm: correct comments regarding do_fault_around() mm: numa: do not trap faults on shared data section pages. hugetlb, mbind: fall back to default policy if vma is NULL hugetlb, mempolicy: fix the mbind hugetlb migration mm, hugetlb: further simplify hugetlb allocation API mm, hugetlb: get rid of surplus page accounting tricks mm, hugetlb: do not rely on overcommit limit during migration mm, hugetlb: integrate giga hugetlb more naturally to the allocation path mm, hugetlb: unify core page allocation accounting and initialization mm/memcontrol.c: try harder to decrease [memory,memsw].limit_in_bytes mm/memcontrol.c: make local symbol static mm/hmm: fix uninitialized use of 'entry' in hmm_vma_walk_pmd() include/linux/mmzone.h: fix explanation of lower bits in the SPARSEMEM mem_map pointer mm/compaction.c: fix comment for try_to_compact_pages() mm/page_ext.c: make page_ext_init a noop when CONFIG_PAGE_EXTENSION but nothing uses it zsmalloc: use U suffix for negative literals being shifted ...
| * | mm, hugetlb: remove hugepages_treat_as_movable sysctlMichal Hocko2018-02-011-25/+0
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | hugepages_treat_as_movable has been introduced by 396faf0303d2 ("Allow huge page allocations to use GFP_HIGH_MOVABLE") to allow hugetlb allocations from ZONE_MOVABLE even when hugetlb pages were not migrateable. The purpose of the movable zone was different at the time. It aimed at reducing memory fragmentation and hugetlb pages being long lived and large werre not contributing to the fragmentation so it was acceptable to use the zone back then. Things have changed though and the primary purpose of the zone became migratability guarantee. If we allow non migrateable hugetlb pages to be in ZONE_MOVABLE memory hotplug might fail to offline the memory. Remove the knob and only rely on hugepage_migration_supported to allow movable zones. Mel said: : Primarily it was aimed at allowing the hugetlb pool to safely shrink with : the ability to grow it again. The use case was for batched jobs, some of : which needed huge pages and others that did not but didn't want the memory : useless pinned in the huge pages pool. : : I suspect that more users rely on THP than hugetlbfs for flexible use of : huge pages with fallback options so I think that removing the option : should be ok. Link: http://lkml.kernel.org/r/20171003072619.8654-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Alexandru Moise <00moses.alexander00@gmail.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Alexandru Moise <00moses.alexander00@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* / net: Clarify dev_weight documentation for LRO and GRO_HW.Michael Chan2017-12-201-1/+3
|/ | | | | | Reported-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Revert "mm/page-writeback.c: print a warning if the vm dirtiness settings ↵Michal Hocko2017-11-301-7/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | are illogical" This reverts commit 0f6d24f87856 ("mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical") because it causes false positive warnings during OOM situations as noticed by Tetsuo Handa: Node 0 active_anon:3525940kB inactive_anon:8372kB active_file:216kB inactive_file:1872kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:2504kB dirty:52kB writeback:0kB shmem:8660kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 636928kB writeback_tmp:0kB unstable:0kB all_unreclaimable? yes Node 0 DMA free:14848kB min:284kB low:352kB high:420kB active_anon:992kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15988kB managed:15904kB mlocked:0kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 2687 3645 3645 Node 0 DMA32 free:53004kB min:49608kB low:62008kB high:74408kB active_anon:2712648kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:3129216kB managed:2773132kB mlocked:0kB kernel_stack:96kB pagetables:5096kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB lowmem_reserve[]: 0 0 958 958 Node 0 Normal free:17140kB min:17684kB low:22104kB high:26524kB active_anon:812300kB inactive_anon:8372kB active_file:1228kB inactive_file:1868kB unevictable:0kB writepending:52kB present:1048576kB managed:981224kB mlocked:0kB kernel_stack:3520kB pagetables:8552kB bounce:0kB free_pcp:120kB local_pcp:120kB free_cma:0kB lowmem_reserve[]: 0 0 0 0 [...] Out of memory: Kill process 8459 (a.out) score 999 or sacrifice child Killed process 8459 (a.out) total-vm:4180kB, anon-rss:88kB, file-rss:0kB, shmem-rss:0kB oom_reaper: reaped process 8459 (a.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB vm direct limit must be set greater than background limit. The problem is that both thresh and bg_thresh will be 0 if available_memory is less than 4 pages when evaluating global_dirtyable_memory. While this might be worked around the whole point of the warning is dubious at best. We do rely on admins to do sensible things when changing tunable knobs. Dirty memory writeback knobs are not any special in that regards so revert the warning rather than adding more hacks to work this around. Debugged by Yafang Shao. Link: http://lkml.kernel.org/r/20171127091939.tahb77nznytcxw55@dhcp22.suse.cz Fixes: 0f6d24f87856 ("mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Yafang Shao <laoar.shao@gmail.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Documentation/sysctl/vm.txt: fix typoKangmin Park2017-11-181-1/+1
| | | | | | | | | Link: http://lkml.kernel.org/r/CAKW4uUyCi=PnKf3epgFVz8z=1tMtHSOHNm+fdNxrNw3-THvRCA@mail.gmail.com Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com> Cc: Jiri Kosina <trivial@kernel.org> Cc: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, sysctl: make NUMA stats configurableKemi Wang2017-11-161-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the second step which introduces a tunable interface that allow numa stats configurable for optimizing zone_statistics(), as suggested by Dave Hansen and Ying Huang. ========================================================================= When page allocation performance becomes a bottleneck and you can tolerate some possible tool breakage and decreased numa counter precision, you can do: echo 0 > /proc/sys/vm/numa_stat In this case, numa counter update is ignored. We can see about *4.8%*(185->176) drop of cpu cycles per single page allocation and reclaim on Jesper's page_bench01 (single thread) and *8.1%*(343->315) drop of cpu cycles per single page allocation and reclaim on Jesper's page_bench03 (88 threads) running on a 2-Socket Broadwell-based server (88 threads, 126G memory). Benchmark link provided by Jesper D Brouer (increase loop times to 10000000): https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench ========================================================================= When page allocation performance is not a bottleneck and you want all tooling to work, you can do: echo 1 > /proc/sys/vm/numa_stat This is system default setting. Many thanks to Michal Hocko, Dave Hansen, Ying Huang and Vlastimil Babka for comments to help improve the original patch. [keescook@chromium.org: make sure mutex is a global static] Link: http://lkml.kernel.org/r/20171107213809.GA4314@beast Link: http://lkml.kernel.org/r/1508290927-8518-1-git-send-email-kemi.wang@intel.com Signed-off-by: Kemi Wang <kemi.wang@intel.com> Signed-off-by: Kees Cook <keescook@chromium.org> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com> Suggested-by: Dave Hansen <dave.hansen@intel.com> Suggested-by: Ying Huang <ying.huang@intel.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Luis R . Rodriguez" <mcgrof@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christopher Lameter <cl@linux.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: consolidate page table accountingKirill A. Shutemov2017-11-161-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, we account page tables separately for each page table level, but that's redundant -- we only make use of total memory allocated to page tables for oom_badness calculation. We also provide the information to userspace, but it has dubious value there too. This patch switches page table accounting to single counter. mm->pgtables_bytes is now used to account all page table levels. We use bytes, because page table size for different levels of page table tree may be different. The change has user-visible effect: we don't have VmPMD and VmPUD reported in /proc/[pid]/status. Not sure if anybody uses them. (As alternative, we can always report 0 kB for them.) OOM-killer report is also slightly changed: we now report pgtables_bytes instead of nr_ptes, nr_pmd, nr_puds. Apart from reducing number of counters per-mm, the benefit is that we now calculate oom_badness() more correctly for machines which have different size of page tables depending on level or where page tables are less than a page in size. The only downside can be debuggability because we do not know which page table level could leak. But I do not remember many bugs that would be caught by separate counters so I wouldn't lose sleep over this. [akpm@linux-foundation.org: fix mm/huge_memory.c] Link: http://lkml.kernel.org/r/20171006100651.44742-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> [kirill.shutemov@linux.intel.com: fix build] Link: http://lkml.kernel.org/r/20171016150113.ikfxy3e7zzfvsr4w@black.fi.intel.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: account pud page tablesKirill A. Shutemov2017-11-161-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | On a machine with 5-level paging support a process can allocate significant amount of memory and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PUD page tables. We don't account PUD page tables, only PMD and PTE. We already addressed the same issue for PMD page tables, see commit dc6c9a35b66b ("mm: account pmd page tables to the process"). Introduction of 5-level paging brings the same issue for PUD page tables. The patch expands accounting to PUD level. [kirill.shutemov@linux.intel.com: s/pmd_t/pud_t/] Link: http://lkml.kernel.org/r/20171004074305.x35eh5u7ybbt5kar@black.fi.intel.com [heiko.carstens@de.ibm.com: s390/mm: fix pud table accounting] Link: http://lkml.kernel.org/r/20171103090551.18231-1-heiko.carstens@de.ibm.com Link: http://lkml.kernel.org/r/20171002080427.3320-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page-writeback.c: print a warning if the vm dirtiness settings are illogicalYafang Shao2017-11-161-0/+7
| | | | | | | | | | | | | The vm direct limit setting must be set greater than vm background limit setting. Otherwise print a warning to help the operator to figure out that the vm dirtiness settings is in illogical state. Link: http://lkml.kernel.org/r/1506592464-30962-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* docs: Update binfmt_misc linksTom Saeger2017-10-032-2/+2
| | | | | | | | Documentation/binfmt_misc.txt moved to Documentation/admin-guide/binfmt-misc.rst Signed-off-by: Tom Saeger <tom.saeger@oracle.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* Merge tag 'seccomp-v4.14-rc2' of ↵Linus Torvalds2017-09-231-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull seccomp updates from Kees Cook: "Major additions: - sysctl and seccomp operation to discover available actions (tyhicks) - new per-filter configurable logging infrastructure and sysctl (tyhicks) - SECCOMP_RET_LOG to log allowed syscalls (tyhicks) - SECCOMP_RET_KILL_PROCESS as the new strictest possible action - self-tests for new behaviors" [ This is the seccomp part of the security pull request during the merge window that was nixed due to unrelated problems - Linus ] * tag 'seccomp-v4.14-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: samples: Unrename SECCOMP_RET_KILL selftests/seccomp: Test thread vs process killing seccomp: Implement SECCOMP_RET_KILL_PROCESS action seccomp: Introduce SECCOMP_RET_KILL_PROCESS seccomp: Rename SECCOMP_RET_KILL to SECCOMP_RET_KILL_THREAD seccomp: Action to log before allowing seccomp: Filter flag to log all actions except SECCOMP_RET_ALLOW seccomp: Selftest for detection of filter flag support seccomp: Sysctl to configure actions that are allowed to be logged seccomp: Operation for checking if an action is available seccomp: Sysctl to display available actions seccomp: Provide matching filter for introspection selftests/seccomp: Refactor RET_ERRNO tests selftests/seccomp: Add simple seccomp overhead benchmark selftests/seccomp: Add tests for basic ptrace actions
| * seccomp: Sysctl to display available actionsTyler Hicks2017-08-141-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch creates a read-only sysctl containing an ordered list of seccomp actions that the kernel supports. The ordering, from left to right, is the lowest action value (kill) to the highest action value (allow). Currently, a read of the sysctl file would return "kill trap errno trace allow". The contents of this sysctl file can be useful for userspace code as well as the system administrator. The path to the sysctl is: /proc/sys/kernel/seccomp/actions_avail libseccomp and other userspace code can easily determine which actions the current kernel supports. The set of actions supported by the current kernel may be different than the set of action macros found in kernel headers that were installed where the userspace code was built. In addition, this sysctl will allow system administrators to know which actions are supported by the kernel and make it easier to configure exactly what seccomp logs through the audit subsystem. Support for this level of logging configuration will come in a future patch. Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: Kees Cook <keescook@chromium.org>
* | Merge branch 'akpm' (patches from Andrew)Linus Torvalds2017-09-071-1/+3
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge updates from Andrew Morton: - various misc bits - DAX updates - OCFS2 - most of MM * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (119 commits) mm,fork: introduce MADV_WIPEONFORK x86,mpx: make mpx depend on x86-64 to free up VMA flag mm: add /proc/pid/smaps_rollup mm: hugetlb: clear target sub-page last when clearing huge page mm: oom: let oom_reap_task and exit_mmap run concurrently swap: choose swap device according to numa node mm: replace TIF_MEMDIE checks by tsk_is_oom_victim mm, oom: do not rely on TIF_MEMDIE for memory reserves access z3fold: use per-cpu unbuddied lists mm, swap: don't use VMA based swap readahead if HDD is used as swap mm, swap: add sysfs interface for VMA based swap readahead mm, swap: VMA based swap readahead mm, swap: fix swap readahead marking mm, swap: add swap readahead hit statistics mm/vmalloc.c: don't reinvent the wheel but use existing llist API mm/vmstat.c: fix wrong comment selftests/memfd: add memfd_create hugetlbfs selftest mm/shmem: add hugetlbfs support to memfd_create() mm, devm_memremap_pages: use multi-order radix for ZONE_DEVICE lookups mm/vmalloc.c: halve the number of comparisons performed in pcpu_get_vm_areas() ...
| * | mm, page_alloc: rip out ZONELIST_ORDER_ZONEMichal Hocko2017-09-071-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "cleanup zonelists initialization", v1. This is aimed at cleaning up the zonelists initialization code we have but the primary motivation was bug report [2] which got resolved but the usage of stop_machine is just too ugly to live. Most patches are straightforward but 3 of them need a special consideration. Patch 1 removes zone ordered zonelists completely. I am CCing linux-api because this is a user visible change. As I argue in the patch description I do not think we have a strong usecase for it these days. I have kept sysctl in place and warn into the log if somebody tries to configure zone lists ordering. If somebody has a real usecase for it we can revert this patch but I do not expect anybody will actually notice runtime differences. This patch is not strictly needed for the rest but it made patch 6 easier to implement. Patch 7 removes stop_machine from build_all_zonelists without adding any special synchronization between iterators and updater which I _believe_ is acceptable as explained in the changelog. I hope I am not missing anything. Patch 8 then removes zonelists_mutex which is kind of ugly as well and not really needed AFAICS but a care should be taken when double checking my thinking. This patch (of 9): Supporting zone ordered zonelists costs us just a lot of code while the usefulness is arguable if existent at all. Mel has already made node ordering default on 64b systems. 32b systems are still using ZONELIST_ORDER_ZONE because it is considered better to fallback to a different NUMA node rather than consume precious lowmem zones. This argument is, however, weaken by the fact that the memory reclaim has been reworked to be node rather than zone oriented. This means that lowmem requests have to skip over all highmem pages on LRUs already and so zone ordering doesn't save the reclaim time much. So the only advantage of the zone ordering is under a light memory pressure when highmem requests do not ever hit into lowmem zones and the lowmem pressure doesn't need to reclaim. Considering that 32b NUMA systems are rather suboptimal already and it is generally advisable to use 64b kernel on such a HW I believe we should rather care about the code maintainability and just get rid of ZONELIST_ORDER_ZONE altogether. Keep systcl in place and warn if somebody tries to set zone ordering either from kernel command line or the sysctl. [mhocko@suse.com: reading vm.numa_zonelist_order will never terminate] Link: http://lkml.kernel.org/r/20170721143915.14161-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Cc: <linux-api@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds2017-09-061-1/+1
|\ \ \ | |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull networking updates from David Miller: 1) Support ipv6 checksum offload in sunvnet driver, from Shannon Nelson. 2) Move to RB-tree instead of custom AVL code in inetpeer, from Eric Dumazet. 3) Allow generic XDP to work on virtual devices, from John Fastabend. 4) Add bpf device maps and XDP_REDIRECT, which can be used to build arbitrary switching frameworks using XDP. From John Fastabend. 5) Remove UFO offloads from the tree, gave us little other than bugs. 6) Remove the IPSEC flow cache, from Florian Westphal. 7) Support ipv6 route offload in mlxsw driver. 8) Support VF representors in bnxt_en, from Sathya Perla. 9) Add support for forward error correction modes to ethtool, from Vidya Sagar Ravipati. 10) Add time filter for packet scheduler action dumping, from Jamal Hadi Salim. 11) Extend the zerocopy sendmsg() used by virtio and tap to regular sockets via MSG_ZEROCOPY. From Willem de Bruijn. 12) Significantly rework value tracking in the BPF verifier, from Edward Cree. 13) Add new jump instructions to eBPF, from Daniel Borkmann. 14) Rework rtnetlink plumbing so that operations can be run without taking the RTNL semaphore. From Florian Westphal. 15) Support XDP in tap driver, from Jason Wang. 16) Add 32-bit eBPF JIT for ARM, from Shubham Bansal. 17) Add Huawei hinic ethernet driver. 18) Allow to report MD5 keys in TCP inet_diag dumps, from Ivan Delalande. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1780 commits) i40e: point wb_desc at the nvm_wb_desc during i40e_read_nvm_aq i40e: avoid NVM acquire deadlock during NVM update drivers: net: xgene: Remove return statement from void function drivers: net: xgene: Configure tx/rx delay for ACPI drivers: net: xgene: Read tx/rx delay for ACPI rocker: fix kcalloc parameter order rds: Fix non-atomic operation on shared flag variable net: sched: don't use GFP_KERNEL under spin lock vhost_net: correctly check tx avail during rx busy polling net: mdio-mux: add mdio_mux parameter to mdio_mux_init() rxrpc: Make service connection lookup always check for retry net: stmmac: Delete dead code for MDIO registration gianfar: Fix Tx flow control deactivation cxgb4: Ignore MPS_TX_INT_CAUSE[Bubble] for T6 cxgb4: Fix pause frame count in t4_get_port_stats cxgb4: fix memory leak tun: rename generic_xdp to skb_xdp tun: reserve extra headroom only when XDP is set net: dsa: bcm_sf2: Configure IMP port TC2QOS mapping net: dsa: bcm_sf2: Advertise number of egress queues ...
| * | bpf, doc: Add arm32 as arch supporting eBPF JITShubham Bansal2017-08-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As eBPF JIT support for arm32 was added recently with commit 39c13c204bb1150d401e27d41a9d8b332be47c49, it seems appropriate to add arm32 as arch with support for eBPF JIT in bpf and sysctl docs as well. Signed-off-by: Shubham Bansal <illusionist.neo@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* | | Merge tag 'perf-core-for-mingo-4.14-20170823' of ↵Ingo Molnar2017-08-241-1/+12
|\ \ \ | |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo: - Expression parser enhancements for metrics (Andi Kleen) - Fix buffer overflow while freeing events in 'perf stat' (Andi Kleen) - Fix static linking with elfutils's libdf and with libunwind in Debian/Ubuntu (Konstantin Khlebnikov) - Tighten detection of BPF events, avoiding matching some other PMU events such as 'cpu/uops_executed.core,cmask=1/' as a .c source file that ended up being considered a BPF event (Andi Kleen) - Add Skylake server uncore JSON vendor events (Andi Kleen) - Add support for printing new mem_info encodings, including 'perf test' checks (Andi Kleen) - Really install manpages via 'make install-man' (Konstantin Khlebnikov) - Fix documentation for perf_event_paranoid and perf_event_mlock_kb sysctls (Konstantin Khlebnikov) Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | perf: Fix documentation for sysctls perf_event_paranoid and perf_event_mlock_kbKonstantin Khlebnikov2017-08-221-1/+12
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | Fix misprint CAP_IOC_LOCK -> CAP_IPC_LOCK. This capability have nothing to do with raw tracepoints. This part is about bypassing mlock limits. Sysctl kernel.perf_event_paranoid = -1 allows raw and ftrace function tracepoints without CAP_SYS_ADMIN. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/150322916080.129746.11285255474738558340.stgit@buzz Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
* | bpf, doc: also add s390x as arch to sysctl descriptionDaniel Borkmann2017-08-211-0/+1
| | | | | | | | | | | | | | | | | | | | Looks like this was accidentally missed, so still add s390x as supported eBPF JIT arch to bpf_jit_enable. Fixes: 014cd0a368dc ("bpf: Update sysctl documentation to list all supported architectures") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* | bpf, doc: improve sysctl knob descriptionDaniel Borkmann2017-08-181-14/+23
| | | | | | | | | | | | | | | | | | Current context speaking of tcpdump filters is out of date these days, so lets improve the sysctl description for the BPF knobs a bit. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* | bpf: Update sysctl documentation to list all supported architecturesMichael Ellerman2017-08-171-2/+17
|/ | | | | | | | | | | | | The sysctl documentation states that the JIT is only available on x86_64, which is no longer correct. Update the list, and break it out to indicate which architectures support the cBPF JIT (via HAVE_CBPF_JIT) or the eBPF JIT (HAVE_EBPF_JIT). Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* mm: document highmem_is_dirtyable sysctlMichal Hocko2017-07-111-0/+20
| | | | | | | | | | | | | | | | It seems that there are still people using 32b kernels which a lot of memory and the IO tend to suck a lot for them by default. Mostly because writers are throttled too when the lowmem is used. We have highmem_is_dirtyable to work around that issue but it seems we never bothered to document it. Let's do it now, finally. Link: http://lkml.kernel.org/r/20170626093200.18958-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alkis Georgopoulos <alkisg@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuningMatthew Whitehead2017-04-211-1/+10
| | | | | | | | | | | | | | | | Constants used for tuning are generally a bad idea, especially as hardware changes over time. Replace the constant 2 jiffies with sysctl variable netdev_budget_usecs to enable sysadmins to tune the softirq processing. Also document the variable. For example, a very fast machine might tune this to 1000 microseconds, while my regression testing 486DX-25 needs it to be 4000 microseconds on a nearly idle network to prevent time_squeeze from being incremented. Version 2: changed jiffies to microseconds for predictable units. Signed-off-by: Matthew Whitehead <tedheadster@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Merge tag 'docs-4.11-fixes' of git://git.lwn.net/linuxLinus Torvalds2017-03-041-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation fixes from Jonathan Corbet: "A few fixes for the docs tree, including one for a 4.11 build regression" * tag 'docs-4.11-fixes' of git://git.lwn.net/linux: Documentation/sphinx: fix primary_domain configuration docs: Fix htmldocs build failure doc/ko_KR/memory-barriers: Update control-dependencies section pcieaer doc: update the link Documentation: Update path to sysrq.txt
| * Documentation: Update path to sysrq.txtKrzysztof Kozlowski2017-03-031-1/+1
| | | | | | | | | | | | | | | | | | Commit 9d85025b0418 ("docs-rst: create an user's manual book") moved the sysrq.txt leaving old paths in the kernel docs. Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Reviewed-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | mm, madvise: fail with ENOMEM when splitting vma will hit max_map_countDavid Rientjes2017-02-251-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If madvise(2) advice will result in the underlying vma being split and the number of areas mapped by the process will exceed /proc/sys/vm/max_map_count as a result, return ENOMEM instead of EAGAIN. EAGAIN is returned by madvise(2) when a kernel resource, such as slab, is temporarily unavailable. It indicates that userspace should retry the advice in the near future. This is important for advice such as MADV_DONTNEED which is often used by malloc implementations to free memory back to the system: we really do want to free memory back when madvise(2) returns EAGAIN because slab allocations (for vmas, anon_vmas, or mempolicies) cannot be allocated. Encountering /proc/sys/vm/max_map_count is not a temporary failure, however, so return ENOMEM to indicate this is a more serious issue. A followup patch to the man page will specify this behavior. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701241431120.42507@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | bpf: make jited programs visible in tracesDaniel Borkmann2017-02-171-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Long standing issue with JITed programs is that stack traces from function tracing check whether a given address is kernel code through {__,}kernel_text_address(), which checks for code in core kernel, modules and dynamically allocated ftrace trampolines. But what is still missing is BPF JITed programs (interpreted programs are not an issue as __bpf_prog_run() will be attributed to them), thus when a stack trace is triggered, the code walking the stack won't see any of the JITed ones. The same for address correlation done from user space via reading /proc/kallsyms. This is read by tools like perf, but the latter is also useful for permanent live tracing with eBPF itself in combination with stack maps when other eBPF types are part of the callchain. See offwaketime example on dumping stack from a map. This work tries to tackle that issue by making the addresses and symbols known to the kernel. The lookup from *kernel_text_address() is implemented through a latched RB tree that can be read under RCU in fast-path that is also shared for symbol/size/offset lookup for a specific given address in kallsyms. The slow-path iteration through all symbols in the seq file done via RCU list, which holds a tiny fraction of all exported ksyms, usually below 0.1 percent. Function symbols are exported as bpf_prog_<tag>, in order to aide debugging and attribution. This facility is currently enabled for root-only when bpf_jit_kallsyms is set to 1, and disabled if hardening is active in any mode. The rationale behind this is that still a lot of systems ship with world read permissions on kallsyms thus addresses should not get suddenly exposed for them. If that situation gets much better in future, we always have the option to change the default on this. Likewise, unprivileged programs are not allowed to add entries there either, but that is less of a concern as most such programs types relevant in this context are for root-only anyway. If enabled, call graphs and stack traces will then show a correct attribution; one example is illustrated below, where the trace is now visible in tooling such as perf script --kallsyms=/proc/kallsyms and friends. Before: 7fff8166889d bpf_clone_redirect+0x80007f0020ed (/lib/modules/4.9.0-rc8+/build/vmlinux) f5d80 __sendmsg_nocancel+0xffff006451f1a007 (/usr/lib64/libc-2.18.so) After: 7fff816688b7 bpf_clone_redirect+0x80007f002107 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fffa0575728 bpf_prog_33c45a467c9e061a+0x8000600020fb (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fffa07ef1fc cls_bpf_classify+0x8000600020dc (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff81678b68 tc_classify+0x80007f002078 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8164d40b __netif_receive_skb_core+0x80007f0025fb (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8164d718 __netif_receive_skb+0x80007f002018 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8164e565 process_backlog+0x80007f002095 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8164dc71 net_rx_action+0x80007f002231 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff81767461 __softirqentry_text_start+0x80007f0020d1 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff817658ac do_softirq_own_stack+0x80007f00201c (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff810a2c20 do_softirq+0x80007f002050 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff810a2cb5 __local_bh_enable_ip+0x80007f002085 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8168d452 ip_finish_output2+0x80007f002152 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8168ea3d ip_finish_output+0x80007f00217d (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff8168f2af ip_output+0x80007f00203f (/lib/modules/4.9.0-rc8+/build/vmlinux) [...] 7fff81005854 do_syscall_64+0x80007f002054 (/lib/modules/4.9.0-rc8+/build/vmlinux) 7fff817649eb return_from_SYSCALL_64+0x80007f002000 (/lib/modules/4.9.0-rc8+/build/vmlinux) f5d80 __sendmsg_nocancel+0xffff01c484812007 (/usr/lib64/libc-2.18.so) Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
* | net: dev_weight: TX/RX orthogonalityMatthias Tafelmeier2016-12-291-0/+21
|/ | | | | | | | | | | | | | | | | | | | | | | Oftenly, introducing side effects on packet processing on the other half of the stack by adjusting one of TX/RX via sysctl is not desirable. There are cases of demand for asymmetric, orthogonal configurability. This holds true especially for nodes where RPS for RFS usage on top is configured and therefore use the 'old dev_weight'. This is quite a common base configuration setup nowadays, even with NICs of superior processing support (e.g. aRFS). A good example use case are nodes acting as noSQL data bases with a large number of tiny requests and rather fewer but large packets as responses. It's affordable to have large budget and rx dev_weights for the requests. But as a side effect having this large a number on TX processed in one run can overwhelm drivers. This patch therefore introduces an independent configurability via sysctl to userland. Signed-off-by: Matthias Tafelmeier <matthias.tafelmeier@gmx.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* Merge tag 'docs-4.10' of git://git.lwn.net/linuxLinus Torvalds2016-12-131-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation update from Jonathan Corbet: "These are the documentation changes for 4.10. It's another busy cycle for the docs tree, as the sphinx conversion continues. Highlights include: - Further work on PDF output, which remains a bit of a pain but should be more solid now. - Five more DocBook template files converted to Sphinx. Only 27 to go... Lots of plain-text files have also been converted and integrated. - Images in binary formats have been replaced with more source-friendly versions. - Various bits of organizational work, including the renaming of various files discussed at the kernel summit. - New documentation for the device_link mechanism. ... and, of course, lots of typo fixes and small updates" * tag 'docs-4.10' of git://git.lwn.net/linux: (193 commits) dma-buf: Extract dma-buf.rst Update Documentation/00-INDEX docs: 00-INDEX: document directories/files with no docs docs: 00-INDEX: remove non-existing entries docs: 00-INDEX: add missing entries for documentation files/dirs docs: 00-INDEX: consolidate process/ and admin-guide/ description scripts: add a script to check if Documentation/00-INDEX is sane Docs: change sh -> awk in REPORTING-BUGS Documentation/core-api/device_link: Add initial documentation core-api: remove an unexpected unident ppc/idle: Add documentation for powersave=off Doc: Correct typo, "Introdution" => "Introduction" Documentation/atomic_ops.txt: convert to ReST markup Documentation/local_ops.txt: convert to ReST markup Documentation/assoc_array.txt: convert to ReST markup docs-rst: parse-headers.pl: cleanup the documentation docs-rst: fix media cleandocs target docs-rst: media/Makefile: reorganize the rules docs-rst: media: build SVG from graphviz files docs-rst: replace bayer.png by a SVG image ...
| * docs: fix locations of several documents that got movedMauro Carvalho Chehab2016-10-241-2/+2
| | | | | | | | | | | | | | | | The previous patch renamed several files that are cross-referenced along the Kernel documentation. Adjust the links to point to the right places. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
* | x86/dumpstack: Remove raw stack dumpJosh Poimboeuf2016-10-251-8/+0
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For mostly historical reasons, the x86 oops dump shows the raw stack values: ... [registers] Stack: ffff880079af7350 ffff880079905400 0000000000000000 ffffc900008f3ae0 ffffffffa0196610 0000000000000001 00010000ffffffff 0000000087654321 0000000000000002 0000000000000000 0000000000000000 0000000000000000 Call Trace: ... This seems to be an artifact from long ago, and probably isn't needed anymore. It generally just adds noise to the dump, and it can be actively harmful because it leaks kernel addresses. Linus says: "The stack dump actually goes back to forever, and it used to be useful back in 1992 or so. But it used to be useful mainly because stacks were simpler and we didn't have very good call traces anyway. I definitely remember having used them - I just do not remember having used them in the last ten+ years. Of course, it's still true that if you can trigger an oops, you've likely already lost the security game, but since the stack dump is so useless, let's aim to just remove it and make games like the above harder." This also removes the related 'kstack=' cmdline option and the 'kstack_depth_to_print' sysctl. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/e83bd50df52d8fe88e94d2566426ae40d813bf8f.1477405374.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* mnt: Add a per mount namespace limit on the number of mountsEric W. Biederman2016-09-301-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | CAI Qian <caiqian@redhat.com> pointed out that the semantics of shared subtrees make it possible to create an exponentially increasing number of mounts in a mount namespace. mkdir /tmp/1 /tmp/2 mount --make-rshared / for i in $(seq 1 20) ; do mount --bind /tmp/1 /tmp/2 ; done Will create create 2^20 or 1048576 mounts, which is a practical problem as some people have managed to hit this by accident. As such CVE-2016-6213 was assigned. Ian Kent <raven@themaw.net> described the situation for autofs users as follows: > The number of mounts for direct mount maps is usually not very large because of > the way they are implemented, large direct mount maps can have performance > problems. There can be anywhere from a few (likely case a few hundred) to less > than 10000, plus mounts that have been triggered and not yet expired. > > Indirect mounts have one autofs mount at the root plus the number of mounts that > have been triggered and not yet expired. > > The number of autofs indirect map entries can range from a few to the common > case of several thousand and in rare cases up to between 30000 and 50000. I've > not heard of people with maps larger than 50000 entries. > > The larger the number of map entries the greater the possibility for a large > number of active mounts so it's not hard to expect cases of a 1000 or somewhat > more active mounts. So I am setting the default number of mounts allowed per mount namespace at 100,000. This is more than enough for any use case I know of, but small enough to quickly stop an exponential increase in mounts. Which should be perfect to catch misconfigurations and malfunctioning programs. For anyone who needs a higher limit this can be changed by writing to the new /proc/sys/fs/mount-max sysctl. Tested-by: CAI Qian <caiqian@redhat.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* userns; Document per user per user namespace limits.Eric W. Biederman2016-09-222-0/+67
| | | | Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* printk: add kernel parameter to control writes to /dev/kmsgBorislav Petkov2016-08-031-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a "printk.devkmsg" kernel command line parameter which controls how userspace writes into /dev/kmsg. It has three options: * ratelimit - ratelimit logging from userspace. * on - unlimited logging from userspace * off - logging from userspace gets ignored The default setting is to ratelimit the messages written to it. This changes the kernel default setting of "on" to "ratelimit" and we do that because we want to keep userspace spamming /dev/kmsg to sane levels. This is especially moot when a small kernel log buffer wraps around and messages get lost. So the ratelimiting setting should be a sane setting where kernel messages should have a bit higher chance of survival from all the spamming. It additionally does not limit logging to /dev/kmsg while the system is booting if we haven't disabled it on the command line. Furthermore, we can control the logging from a lower priority sysctl interface - kernel.printk_devkmsg. That interface will succeed only if printk.devkmsg *hasn't* been supplied on the command line. If it has, then printk.devkmsg is a one-time setting which remains for the duration of the system lifetime. This "locking" of the setting is to prevent userspace from changing the logging on us through sysctl(2). This patch is based on previous patches from Linus and Steven. [bp@suse.de: fixes] Link: http://lkml.kernel.org/r/20160719072344.GC25563@nazgul.tnic Link: http://lkml.kernel.org/r/20160716061745.15795-3-bp@alien8.de Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Dave Young <dyoung@redhat.com> Cc: Franck Bui <fbui@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'docs-for-linus' of git://git.lwn.net/linuxLinus Torvalds2016-07-261-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation updates from Jonathan Corbet: "Some big changes this month, headlined by the addition of a new formatted documentation mechanism based on the Sphinx system. The objectives here are to make it easier to create better-integrated (and more attractive) documents while (eventually) dumping our one-of-a-kind, cobbled-together system for something that is widely used and maintained by others. There's a fair amount of information what's being done, why, and how to use it in: https://lwn.net/Articles/692704/ https://lwn.net/Articles/692705/ Closer to home, Documentation/kernel-documentation.rst describes how it works. For now, the new system exists alongside the old one; you should soon see the GPU documentation converted over in the DRM pull and some significant media conversion work as well. Once all the docs have been moved over and we're convinced that the rough edges (of which are are a few) have been smoothed over, the DocBook-based stuff should go away. Primary credit is to Jani Nikula for doing the heavy lifting to make this stuff actually work; there has also been notable effort from Markus Heiser, Daniel Vetter, and Mauro Carvalho Chehab. Expect a couple of conflicts on the new index.rst file over the course of the merge window; they are trivially resolvable. That file may be a bit of a conflict magnet in the short term, but I don't expect that situation to last for any real length of time. Beyond that, of course, we have the usual collection of tweaks, updates, and typo fixes" * tag 'docs-for-linus' of git://git.lwn.net/linux: (77 commits) doc-rst: kernel-doc: fix handling of address_space tags Revert "doc/sphinx: Enable keep_warnings" doc-rst: kernel-doc directive, fix state machine reporter docs: deprecate kernel-doc-nano-HOWTO.txt doc/sphinx: Enable keep_warnings Documentation: add watermark_scale_factor to the list of vm systcl file kernel-doc: Fix up warning output docs: Get rid of some kernel-documentation warnings doc-rst: add an option to ignore DocBooks when generating docs workqueue: Fix a typo in workqueue.txt Doc: ocfs: Fix typo in filesystems/ocfs2-online-filecheck.txt Documentation/sphinx: skip build if user requested specific DOCBOOKS Documentation: add cleanmediadocs to the documentation targets Add .pyc files to .gitignore Doc: PM: Fix a typo in intel_powerclamp.txt doc-rst: flat-table directive - initial implementation Documentation: add meta-documentation for Sphinx and kernel-doc Documentation: tiny typo fix in usb/gadget_multi.txt Documentation: fix wrong value in md.txt bcache: documentation formatting, edited for clarity, stripe alignment notes ...
| * Documentation: add watermark_scale_factor to the list of vm systcl fileJerome Marchand2016-07-181-0/+1
| | | | | | | | | | | | | | | | | | | | | | Commit 795ae7a0de6b ("mm: scale kswapd watermarks in proportion to memory") properly added the description of the new knob to Documentation/sysctl/vm.txt, but forgot to add it to the list of files in /proc/sys/vm. Let's fix that. Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | rcu: sysctl: Panic on RCU StallDaniel Bristot de Oliveira2016-06-161-0/+12
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is not always easy to determine the cause of an RCU stall just by analysing the RCU stall messages, mainly when the problem is caused by the indirect starvation of rcu threads. For example, when preempt_rcu is not awakened due to the starvation of a timer softirq. We have been hard coding panic() in the RCU stall functions for some time while testing the kernel-rt. But this is not possible in some scenarios, like when supporting customers. This patch implements the sysctl kernel.panic_on_rcu_stall. If set to 1, the system will panic() when an RCU stall takes place, enabling the capture of a vmcore. The vmcore provides a way to analyze all kernel/tasks states, helping out to point to the culprit and the solution for the stall. The kernel.panic_on_rcu_stall sysctl is disabled by default. Changes from v1: - Fixed a typo in the git log - The if(sysctl_panic_on_rcu_stall) panic() is in a static function - Fixed the CONFIG_TINY_RCU compilation issue - The var sysctl_panic_on_rcu_stall is now __read_mostly Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Arnaldo Carvalho de Melo <acme@kernel.org> Tested-by: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com> Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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