linux-kernel - Re: [PATCH v1 4/4] selftests/mm: Add test about uprobe pte be orphan during vma merge

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Message-ID: <9117d6d8-df01-4949-a695-29cafe7fe65f@lucifer.local>
Date: Fri, 30 May 2025 12:32:50 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Pu Lehui <pulehui@...weicloud.com>
Cc: mhiramat@...nel.org, oleg@...hat.com, peterz@...radead.org,
        akpm@...ux-foundation.org, Liam.Howlett@...cle.com, vbabka@...e.cz,
        jannh@...gle.com, pfalcato@...e.de, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        pulehui@...wei.com
Subject: Re: [PATCH v1 4/4] selftests/mm: Add test about uprobe pte be orphan
 during vma merge

On Thu, May 29, 2025 at 03:56:50PM +0000, Pu Lehui wrote:
> From: Pu Lehui <pulehui@...wei.com>
>
> Add test about uprobe pte be orphan during vma merge.
>
> Signed-off-by: Pu Lehui <pulehui@...wei.com>
> ---
>  tools/testing/selftests/mm/merge.c | 42 ++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
>
> diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c
> index c76646cdf6e6..8e1f38d23384 100644
> --- a/tools/testing/selftests/mm/merge.c
> +++ b/tools/testing/selftests/mm/merge.c
> @@ -2,11 +2,13 @@
>
>  #define _GNU_SOURCE
>  #include "../kselftest_harness.h"
> +#include <fcntl.h>
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <unistd.h>
>  #include <sys/mman.h>
>  #include <sys/wait.h>
> +#include <linux/perf_event.h>
>  #include "vm_util.h"

Need to include sys/syscall.h...

>
>  FIXTURE(merge)
> @@ -452,4 +454,44 @@ TEST_F(merge, forked_source_vma)
>  	ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr2 + 5 * page_size);
>  }
>
> +TEST_F(merge, handle_uprobe_upon_merged_vma)
> +{
> +	const size_t attr_sz = sizeof(struct perf_event_attr);
> +	unsigned int page_size = self->page_size;
> +	const char *probe_file = "./foo";
> +	char *carveout = self->carveout;
> +	struct perf_event_attr attr;
> +	unsigned long type;
> +	void *ptr1, *ptr2;
> +	int fd;
> +
> +	fd = open(probe_file, O_RDWR|O_CREAT, 0600);
> +	ASSERT_GE(fd, 0);
> +
> +	ASSERT_EQ(ftruncate(fd, page_size), 0);
> +	ASSERT_EQ(read_sysfs("/sys/bus/event_source/devices/uprobe/type", &type), 0);
> +
> +	memset(&attr, 0, attr_sz);
> +	attr.size = attr_sz;
> +	attr.type = type;
> +	attr.config1 = (__u64)(long)probe_file;
> +	attr.config2 = 0x0;
> +
> +	ASSERT_GE(syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0), 0);

...Because this results in:

In file included from merge.c:4:
merge.c: In function ‘merge_handle_uprobe_upon_merged_vma’:
merge.c:480:27: error: ‘__NR_perf_event_open’ undeclared (first use in this function)
  480 |         ASSERT_GE(syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0), 0);

Otherwise :>)

> +
> +	ptr1 = mmap(&carveout[page_size], 10 * page_size, PROT_EXEC,
> +		    MAP_PRIVATE | MAP_FIXED, fd, 0);
> +	ASSERT_NE(ptr1, MAP_FAILED);
> +
> +	ptr2 = mremap(ptr1, page_size, 2 * page_size,
> +		      MREMAP_MAYMOVE | MREMAP_FIXED, ptr1 + 5 * page_size);
> +	ASSERT_NE(ptr2, MAP_FAILED);
> +
> +	ASSERT_NE(mremap(ptr2, page_size, page_size,
> +			 MREMAP_MAYMOVE | MREMAP_FIXED, ptr1), MAP_FAILED);
> +
> +	close(fd);
> +	remove(probe_file);
> +}
> +
>  TEST_HARNESS_MAIN
> --
> 2.34.1
>