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Saravanan Vajravel a195a42dd2 RDMA/mad: Improve handling of timed out WRs of mad agent 
[ Upstream commit 2a777679b8 ]

Current timeout handler of mad agent acquires/releases mad_agent_priv
lock for every timed out WRs. This causes heavy locking contention
when higher no. of WRs are to be handled inside timeout handler.

This leads to softlockup with below trace in some use cases where
rdma-cm path is used to establish connection between peer nodes

Trace:
-----
 BUG: soft lockup - CPU#4 stuck for 26s! [kworker/u128:3:19767]
 CPU: 4 PID: 19767 Comm: kworker/u128:3 Kdump: loaded Tainted: G OE
     -------  ---  5.14.0-427.13.1.el9_4.x86_64 #1
 Hardware name: Dell Inc. PowerEdge R740/01YM03, BIOS 2.4.8 11/26/2019
 Workqueue: ib_mad1 timeout_sends [ib_core]
 RIP: 0010:__do_softirq+0x78/0x2ac
 RSP: 0018:ffffb253449e4f98 EFLAGS: 00000246
 RAX: 00000000ffffffff RBX: 0000000000000000 RCX: 000000000000001f
 RDX: 000000000000001d RSI: 000000003d1879ab RDI: fff363b66fd3a86b
 RBP: ffffb253604cbcd8 R08: 0000009065635f3b R09: 0000000000000000
 R10: 0000000000000040 R11: ffffb253449e4ff8 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000040
 FS:  0000000000000000(0000) GS:ffff8caa1fc80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fd9ec9db900 CR3: 0000000891934006 CR4: 00000000007706e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 PKRU: 55555554
 Call Trace:
  <IRQ>
  ? show_trace_log_lvl+0x1c4/0x2df
  ? show_trace_log_lvl+0x1c4/0x2df
  ? __irq_exit_rcu+0xa1/0xc0
  ? watchdog_timer_fn+0x1b2/0x210
  ? __pfx_watchdog_timer_fn+0x10/0x10
  ? __hrtimer_run_queues+0x127/0x2c0
  ? hrtimer_interrupt+0xfc/0x210
  ? __sysvec_apic_timer_interrupt+0x5c/0x110
  ? sysvec_apic_timer_interrupt+0x37/0x90
  ? asm_sysvec_apic_timer_interrupt+0x16/0x20
  ? __do_softirq+0x78/0x2ac
  ? __do_softirq+0x60/0x2ac
  __irq_exit_rcu+0xa1/0xc0
  sysvec_call_function_single+0x72/0x90
  </IRQ>
  <TASK>
  asm_sysvec_call_function_single+0x16/0x20
 RIP: 0010:_raw_spin_unlock_irq+0x14/0x30
 RSP: 0018:ffffb253604cbd88 EFLAGS: 00000247
 RAX: 000000000001960d RBX: 0000000000000002 RCX: ffff8cad2a064800
 RDX: 000000008020001b RSI: 0000000000000001 RDI: ffff8cad5d39f66c
 RBP: ffff8cad5d39f600 R08: 0000000000000001 R09: 0000000000000000
 R10: ffff8caa443e0c00 R11: ffffb253604cbcd8 R12: ffff8cacb8682538
 R13: 0000000000000005 R14: ffffb253604cbd90 R15: ffff8cad5d39f66c
  cm_process_send_error+0x122/0x1d0 [ib_cm]
  timeout_sends+0x1dd/0x270 [ib_core]
  process_one_work+0x1e2/0x3b0
  ? __pfx_worker_thread+0x10/0x10
  worker_thread+0x50/0x3a0
  ? __pfx_worker_thread+0x10/0x10
  kthread+0xdd/0x100
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x29/0x50
  </TASK>

Simplified timeout handler by creating local list of timed out WRs
and invoke send handler post creating the list. The new method acquires/
releases lock once to fetch the list and hence helps to reduce locking
contetiong when processing higher no. of WRs

Signed-off-by: Saravanan Vajravel <saravanan.vajravel@broadcom.com>
Link: https://lore.kernel.org/r/20240722110325.195085-1-saravanan.vajravel@broadcom.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-10-17 15:24:16 +02:00
arch s390/cpum_sf: Remove WARN_ON_ONCE statements 2024-10-17 15:24:16 +02:00
block blk_iocost: fix more out of bound shifts 2024-10-10 11:57:24 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: simd - Do not call crypto_alloc_tfm during registration 2024-10-10 11:57:26 +02:00
Documentation selftests: Introduce Makefile variable to list shared bash scripts 2024-10-17 15:24:13 +02:00
drivers RDMA/mad: Improve handling of timed out WRs of mad agent 2024-10-17 15:24:16 +02:00
fs ext4: nested locking for xattr inode 2024-10-17 15:24:16 +02:00
include bpf: Prevent tail call between progs attached to different hooks 2024-10-17 15:24:16 +02:00
init rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT 2024-08-29 17:33:29 +02:00
io_uring io_uring/net: harden multishot termination case for recv 2024-10-10 11:58:02 +02:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:47:13 +02:00
kernel bpf: Prevent tail call between progs attached to different hooks 2024-10-17 15:24:16 +02:00
lib lib/build_OID_registry: avoid non-destructive substitution for Perl < 5.13.2 compat 2024-10-17 15:24:13 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: z3fold: deprecate CONFIG_Z3FOLD 2024-10-10 11:58:02 +02:00
net Bluetooth: Fix usage of __hci_cmd_sync_status 2024-10-17 15:24:13 +02:00
rust rust: sync: require T: Sync for LockedBy::access 2024-10-10 11:57:44 +02:00
samples samples/bpf: Fix compilation errors with cf-protection option 2024-10-04 16:29:19 +02:00
scripts kconfig: qconf: fix buffer overflow in debug links 2024-10-10 11:58:01 +02:00
security tomoyo: fallback to realpath if symlink's pathname does not exist 2024-10-10 11:57:57 +02:00
sound ALSA: hda/realtek: cs35l41: Fix device ID / model name 2024-10-17 15:24:09 +02:00
tools ktest.pl: Avoid false positives with grub2 skip regex 2024-10-17 15:24:16 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock 2024-10-04 16:29:47 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-04 16:29:44 +02:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile Linux 6.6.56 2024-10-10 12:50:06 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.