The patch titled
Subject: selftests/mm: virtual_address_range: dump to /dev/null
has been added to the -mm mm-unstable branch. Its filename is
selftests-mm-virtual_address_range-dump-to-dev-null.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mm-virtual_address_range-dump-to-dev-null.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Thomas WeiÃ?schuh <thomas.weissschuh@xxxxxxxxxxxxx>
Subject: selftests/mm: virtual_address_range: dump to /dev/null
Date: Tue, 07 Jan 2025 16:14:47 +0100
During the execution of validate_complete_va_space() a lot of memory is on
the VM subsystem. When running on a low memory subsystem an OOM may be
triggered, when writing to the dump file as the filesystem may also
require memory.
On my test system with 1100MiB physical memory:
Tasks state (memory values in pages):
[ pid ] uid tgid total_vm rss rss_anon rss_file rss_shmem pgtables_bytes swapents oom_score_adj name
[ 57] 0 57 34359215953 695 256 0 439 1064390656 0 0 virtual_address
Out of memory: Killed process 57 (virtual_address) total-vm:137436863812kB, anon-rss:1024kB, file-rss:0kB, shmem-rss:1756kB, UID:0 pgtables:1039444kB oom_score_adj:0
<snip>
fault_in_iov_iter_readable+0x4a/0xd0
generic_perform_write+0x9c/0x280
shmem_file_write_iter+0x86/0x90
vfs_write+0x29c/0x480
ksys_write+0x6c/0xe0
do_syscall_64+0x9e/0x1a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Write the dumped data into /dev/null instead which does not require
additional memory during write(), making the code simpler as a
side-effect.
Link: https://lkml.kernel.org/r/20250107-virtual_address_range-tests-v1-3-3834a2fb47fe@xxxxxxxxxxxxx
Signed-off-by: Thomas WeiÃ?schuh <thomas.weissschuh@xxxxxxxxxxxxx>
Cc: Dev Jain <dev.jain@xxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/mm/virtual_address_range.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/tools/testing/selftests/mm/virtual_address_range.c~selftests-mm-virtual_address_range-dump-to-dev-null
+++ a/tools/testing/selftests/mm/virtual_address_range.c
@@ -103,10 +103,9 @@ static int validate_complete_va_space(vo
FILE *file;
int fd;
- fd = open("va_dump", O_CREAT | O_WRONLY, 0600);
- unlink("va_dump");
+ fd = open("/dev/null", O_WRONLY);
if (fd < 0) {
- ksft_test_result_skip("cannot create or open dump file\n");
+ ksft_test_result_skip("cannot create or open /dev/null\n");
ksft_finished();
}
@@ -152,7 +151,6 @@ static int validate_complete_va_space(vo
while (start_addr + hop < end_addr) {
if (write(fd, (void *)(start_addr + hop), 1) != 1)
return 1;
- lseek(fd, 0, SEEK_SET);
hop += MAP_CHUNK_SIZE;
}
_
Patches currently in -mm which might be from thomas.weissschuh@xxxxxxxxxxxxx are
selftests-mm-virtual_address_range-fix-error-when-commitlimit-1gib.patch
selftests-mm-virtual_address_range-avoid-reading-vvar-mappings.patch
selftests-mm-virtual_address_range-dump-to-dev-null.patch
