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Zheng Yejian ef6b907458 ring-buffer: Fix race while reader and writer are on the same page 
commit 6455b6163d upstream.

When user reads file 'trace_pipe', kernel keeps printing following logs
that warn at "cpu_buffer->reader_page->read > rb_page_size(reader)" in
rb_get_reader_page(). It just looks like there's an infinite loop in
tracing_read_pipe(). This problem occurs several times on arm64 platform
when testing v5.10 and below.

  Call trace:
   rb_get_reader_page+0x248/0x1300
   rb_buffer_peek+0x34/0x160
   ring_buffer_peek+0xbc/0x224
   peek_next_entry+0x98/0xbc
   __find_next_entry+0xc4/0x1c0
   trace_find_next_entry_inc+0x30/0x94
   tracing_read_pipe+0x198/0x304
   vfs_read+0xb4/0x1e0
   ksys_read+0x74/0x100
   __arm64_sys_read+0x24/0x30
   el0_svc_common.constprop.0+0x7c/0x1bc
   do_el0_svc+0x2c/0x94
   el0_svc+0x20/0x30
   el0_sync_handler+0xb0/0xb4
   el0_sync+0x160/0x180

Then I dump the vmcore and look into the problematic per_cpu ring_buffer,
I found that tail_page/commit_page/reader_page are on the same page while
reader_page->read is obviously abnormal:
  tail_page == commit_page == reader_page == {
    .write = 0x100d20,
    .read = 0x8f9f4805,  // Far greater than 0xd20, obviously abnormal!!!
    .entries = 0x10004c,
    .real_end = 0x0,
    .page = {
      .time_stamp = 0x857257416af0,
      .commit = 0xd20,  // This page hasn't been full filled.
      // .data[0...0xd20] seems normal.
    }
 }

The root cause is most likely the race that reader and writer are on the
same page while reader saw an event that not fully committed by writer.

To fix this, add memory barriers to make sure the reader can see the
content of what is committed. Since commit a0fcaaed0c ("ring-buffer: Fix
race between reset page and reading page") has added the read barrier in
rb_get_reader_page(), here we just need to add the write barrier.

Link: https://lore.kernel.org/linux-trace-kernel/20230325021247.2923907-1-zhengyejian1@huawei.com

Cc: stable@vger.kernel.org
Fixes: 77ae365eca ("ring-buffer: make lockless")
Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-04-19 18:01:23 +08:00
arch KVM: s390: pv: fix external interruption loop not always detected 2023-04-19 18:01:18 +08:00
block block: don't allow multiple bios for IOCB_NOWAIT issue 2023-04-19 18:00:13 +08:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2023-04-19 17:50:34 +08:00
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-04-19 17:59:48 +08:00
Documentation dt-bindings: serial: renesas,scif: Fix 4th IRQ for 4-IRQ SCIFs 2023-04-19 18:01:22 +08:00
drivers drm/nouveau/disp: Support more modes by checking with lower bpc 2023-04-19 18:01:23 +08:00
fs fs: drop peer group ids under namespace lock 2023-04-19 18:01:23 +08:00
include ftrace: Mark get_lock_parent_ip() __always_inline 2023-04-19 18:01:23 +08:00
init kbuild: Add CONFIG_PAHOLE_VERSION 2023-04-19 17:59:33 +08:00
io_uring io_uring: avoid null-ptr-deref in io_arm_poll_handler 2023-04-19 18:00:57 +08:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2023-04-19 17:56:54 +08:00
kernel ring-buffer: Fix race while reader and writer are on the same page 2023-04-19 18:01:23 +08:00
lib kobject: Fix slab-out-of-bounds in fill_kobj_path() 2023-04-19 18:00:00 +08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: vmalloc: avoid warn_alloc noise caused by fatal signal 2023-04-19 18:01:23 +08:00
net can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events 2023-04-19 18:01:23 +08:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2023-04-19 17:57:46 +08:00
scripts kconfig: Update config changed flag before calling callback 2023-04-19 18:00:53 +08:00
security keys: Do not cache key in task struct if key is requested from kernel thread 2023-04-19 18:01:01 +08:00
sound ASoC: hdac_hdmi: use set_stream() instead of set_tdm_slots() 2023-04-19 18:01:23 +08:00
tools libbpf: Fix btf_dump's packed struct determination 2023-04-19 18:01:17 +08:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2023-04-19 17:44:58 +08:00
virt KVM: fix memoryleak in kvm_init() 2023-04-19 18:00:47 +08:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS kbuild: Add CONFIG_PAHOLE_VERSION 2023-04-19 17:59:33 +08:00
Makefile kbuild: refactor single builds of *.ko 2023-04-19 18:01:20 +08:00
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