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: <c093f0d7-58b2-492b-bba5-5e1007a78056@huaweicloud.com>
Date: Tue, 3 Jun 2025 15:08:22 +0800
From: Pu Lehui <pulehui@...weicloud.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.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 2025/5/30 19:32, Lorenzo Stoakes wrote:
> 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);
> 

I did not encounter this problem when compiling in the 
tools/testing/selftests/mm directory, but in any case, adding the 
sys/syscall.h header file makes sense.

> 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
>>