WSL2-Linux-Kernel/kernel/events
Zhipeng Xie 56637084e8 perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled
[ Upstream commit 60490e7966 ]

This problem can be reproduced with CONFIG_PERF_USE_VMALLOC enabled on
both x86_64 and aarch64 arch when using sysdig -B(using ebpf)[1].
sysdig -B works fine after rebuilding the kernel with
CONFIG_PERF_USE_VMALLOC disabled.

I tracked it down to the if condition event->rb->nr_pages != nr_pages
in perf_mmap is true when CONFIG_PERF_USE_VMALLOC is enabled where
event->rb->nr_pages = 1 and nr_pages = 2048 resulting perf_mmap to
return -EINVAL. This is because when CONFIG_PERF_USE_VMALLOC is
enabled, rb->nr_pages is always equal to 1.

Arch with CONFIG_PERF_USE_VMALLOC enabled by default:
	arc/arm/csky/mips/sh/sparc/xtensa

Arch with CONFIG_PERF_USE_VMALLOC disabled by default:
	x86_64/aarch64/...

Fix this problem by using data_page_nr()

[1] https://github.com/draios/sysdig

Fixes: 906010b213 ("perf_event: Provide vmalloc() based mmap() backing")
Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220209145417.6495-1-xiezhipeng1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-27 14:38:58 +02:00
..
Makefile
callchain.c uaccess: add force_uaccess_{begin,end} helpers 2020-08-12 10:57:59 -07:00
core.c perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled 2022-04-27 14:38:58 +02:00
hw_breakpoint.c perf/hw_breakpoint: Replace deprecated CPU-hotplug functions 2021-08-26 09:14:36 +02:00
internal.h perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled 2022-04-27 14:38:58 +02:00
ring_buffer.c perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled 2022-04-27 14:38:58 +02:00
uprobes.c Merge branch 'akpm' (patches from Andrew) 2021-06-29 17:29:11 -07:00