Messages in this thread | | | From | Zhipeng Xie <> | Subject | Re: PING: [PATCH v2] perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled | Date | Thu, 17 Mar 2022 21:19:41 -0400 |
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Ping again, sorry for the noise.
On Thu, February 17, 2022 12:54 AM, Zhipeng Xie wrote: > > Hi, Peter > > Could you please review the V2 version? > > On Wed, February 9, 2022 10:54 PM, Zhipeng Xie wrote: > > 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 > > > > Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com> > > --- > > kernel/events/core.c | 2 +- > > kernel/events/internal.h | 5 +++++ > > kernel/events/ring_buffer.c | 5 ----- > > 3 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c > > index 57c7197838db..370292effd32 100644 > > --- a/kernel/events/core.c > > +++ b/kernel/events/core.c > > @@ -6352,7 +6352,7 @@ static int perf_mmap(struct file *file, struct > > vm_area_struct *vma) > > again: > > mutex_lock(&event->mmap_mutex); > > if (event->rb) { > > - if (event->rb->nr_pages != nr_pages) { > > + if (data_page_nr(event->rb) != nr_pages) { > > ret = -EINVAL; > > goto unlock; > > } > > diff --git a/kernel/events/internal.h b/kernel/events/internal.h > > index 082832738c8f..5816c0719dbf 100644 > > --- a/kernel/events/internal.h > > +++ b/kernel/events/internal.h > > @@ -116,6 +116,11 @@ static inline int page_order(struct perf_buffer *rb) > > } > > #endif > > > > +static int data_page_nr(struct perf_buffer *rb) > > +{ > > + return rb->nr_pages << page_order(rb); > > +} > > + > > static inline unsigned long perf_data_size(struct perf_buffer *rb) > > { > > return rb->nr_pages << (PAGE_SHIFT + page_order(rb)); > > diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c > > index 52868716ec35..fb35b926024c 100644 > > --- a/kernel/events/ring_buffer.c > > +++ b/kernel/events/ring_buffer.c > > @@ -859,11 +859,6 @@ void rb_free(struct perf_buffer *rb) > > } > > > > #else > > -static int data_page_nr(struct perf_buffer *rb) > > -{ > > - return rb->nr_pages << page_order(rb); > > -} > > - > > static struct page * > > __perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff) > > { > > -- > > 2.18.1 > > Best Regards, > Zhipeng Xie
Best Regards, Zhipeng Xie
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