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Kan Liang 0252305d29 perf/x86/intel/ds: Unconditionally drain PEBS DS when changing PEBS_DATA_CFG 
commit 9f3de72a0c upstream.

The PEBS kernel warnings can still be observed with the below case.

when the below commands are running in parallel for a while.

  while true;
  do
	perf record --no-buildid -a --intr-regs=AX  \
		    -e cpu/event=0xd0,umask=0x81/pp \
		    -c 10003 -o /dev/null ./triad;
  done &

  while true;
  do
	perf record -e 'cpu/mem-loads,ldlat=3/uP' -W -d -- ./dtlb
  done

The commit b752ea0c28 ("perf/x86/intel/ds: Flush PEBS DS when changing
PEBS_DATA_CFG") intends to flush the entire PEBS buffer before the
hardware is reprogrammed. However, it fails in the above case.

The first perf command utilizes the large PEBS, while the second perf
command only utilizes a single PEBS. When the second perf event is
added, only the n_pebs++. The intel_pmu_pebs_enable() is invoked after
intel_pmu_pebs_add(). So the cpuc->n_pebs == cpuc->n_large_pebs check in
the intel_pmu_drain_large_pebs() fails. The PEBS DS is not flushed.
The new PEBS event should not be taken into account when flushing the
existing PEBS DS.

The check is unnecessary here. Before the hardware is reprogrammed, all
the stale records must be drained unconditionally.

For single PEBS or PEBS-vi-pt, the DS must be empty. The drain_pebs()
can handle the empty case. There is no harm to unconditionally drain the
PEBS DS.

Fixes: b752ea0c28 ("perf/x86/intel/ds: Flush PEBS DS when changing PEBS_DATA_CFG")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241119135504.1463839-2-kan.liang@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-12-19 18:11:21 +01:00
arch perf/x86/intel/ds: Unconditionally drain PEBS DS when changing PEBS_DATA_CFG 2024-12-19 18:11:21 +01:00
block block, bfq: fix bfqq uaf in bfq_limit_depth() 2024-12-09 10:33:00 +01:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-09 10:31:48 +01:00
Documentation PCI: Add 'reset_subordinate' to reset hierarchy below bridge 2024-12-14 20:00:14 +01:00
drivers i3c: master: svc: fix possible assignment of the same address to two devices 2024-12-14 20:00:23 +01:00
fs ocfs2: Revert "ocfs2: fix the la space leak when unmounting an ocfs2 volume" 2024-12-14 20:00:22 +01:00
include ALSA: usb-audio: Update UMP group attributes for GTB blocks, too 2024-12-14 20:00:23 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-09 10:32:46 +01:00
io_uring io_uring/tctx: work around xa_store() allocation error issue 2024-12-14 20:00:17 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-09 10:32:54 +01:00
kernel bpf: Fix UAF via mismatching bpf_prog/attachment RCU flavors 2024-12-19 18:11:21 +01:00
lib lib: stackinit: hide never-taken branch from compiler 2024-12-14 19:59:57 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/damon/vaddr: fix issue in damon_va_evenly_split_region() 2024-12-14 20:00:21 +01:00
net net/smc: fix incorrect SMC-D link group matching logic 2024-12-14 20:00:22 +01:00
rust rust: macros: fix documentation of the paste! macro 2024-12-09 10:32:25 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 20:00:03 +01:00
scripts setlocalversion: work around "git describe" performance 2024-12-14 20:00:17 +01:00
security apparmor: test: Fix memory leak for aa_unpack_strdup() 2024-12-09 10:32:45 +01:00
sound ALSA: usb-audio: Update UMP group attributes for GTB blocks, too 2024-12-14 20:00:23 +01:00
tools selftests/ftrace: adjust offset for kprobe syntax error test 2024-12-14 20:00:21 +01:00
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 6.6.66 2024-12-14 20:00:23 +01:00
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.