on 3/22/2024 10:49 PM, Guenter Roeck wrote: > 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. Thanks for sharing this. I have already turn these configs on, but I use the ext4 tree https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/log/?h=dev which may be the reason why I can't reproduce the issue. I see you have already tested the fix in upstream. Thanks a lot for that! Kemeng > > Guenter >
