On 3/22/24 02:27, Kemeng Shi wrote:
on 3/21/2024 3:16 PM, Kemeng Shi wrote:
on 3/21/2024 12:23 AM, Guenter Roeck wrote:
Hi,
On Wed, Jan 03, 2024 at 06:48:57PM +0800, Kemeng Shi wrote:
Add unit test of ext4_mb_generate_buddy
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
With this and other new ext4 tests test in the tree, I see a variety
of backtraces in the upstream kernel if debug options are enabled.
An example is
[ 6.821447] KTAP version 1
[ 6.821769] # Subtest: test_mb_generate_buddy
[ 6.824787] =============================================================================
[ 6.825568] BUG inode_cache (Tainted: G N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232
...
[ 6.894341] ok 7 ext4_inode_test
[ 6.895411] =============================================================================
[ 6.895777] BUG inode_cache (Tainted: G B N): Padding overwritten. 0xfffff80006223f68-0xfffff80006223f6f @offset=16232
Another example, from another test run, is
[ 3.938551] # Subtest: test_new_blocks_simple
[ 3.947171] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
[ 3.952988] ok 2 block_bits=12 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
[ 3.958403] ok 3 block_bits=16 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
[ 3.958890] =============================================================================
[ 3.959159] BUG inode_cache (Tainted: G N): Padding overwritten. 0xffff8de881adbf68-0xffff8de881adbf6f @offset=16232
Another one:
[ 18.730473] # Subtest: test_new_blocks_simple
[ 18.760547] ok 1 block_bits=10 cluster_bits=3 blocks_per_group=8192 group_count=4 desc_size=64
[ 18.778477] ==================================================================
[ 18.778950] BUG: KFENCE: out-of-bounds write in ext4_mb_init+0x5d7/0xa60
This is just a sample, taken from a quick look at test results.
Are those backtraces expected ? If so, would it be possible to execute the
tests without generating such backtraces ? The backtraces, if intentional,
hide real problems in the noise.
Thanks for the report. The backtrace is not expected, I will look into this. Thansk!
Hi Guenter, I could not reproduce this in my local vm. From the reported backtraces, it's
likely there is a out-of-bounds write to sbi->s_buddy_cache. I try to fix this in [1] and
it works fine in my local vm. I wish this work for you to elimate the reported nosie.
Look forward to your reply, Thanks.
You would need to have CONFIG_SLUB_DEBUG=y, CONFIG_SLUB_DEBUG_ON=y, and CONFIG_KFENCE=y
to see the problems.
Guenter
