On 2/26/22 13:18, Hyeonggon Yoo wrote: > On Fri, Feb 25, 2022 at 07:03:13PM +0100, Vlastimil Babka wrote: >> Hi, >> >> this series combines and revives patches from Oliver's last year >> bachelor thesis (where I was the advisor) that make SLUB's debugfs >> files alloc_traces and free_traces more useful. >> The resubmission was blocked on stackdepot changes that are now merged, >> as explained in patch 2. >> >> Patch 1 is a new preparatory cleanup. >> >> Patch 2 originally submitted here [1], was merged to mainline but >> reverted for stackdepot related issues as explained in the patch. >> >> Patches 3-5 originally submitted as RFC here [2]. In this submission I >> have omitted the new file 'all_objects' (patch 3/3 in [2]) as it might >> be considered too intrusive so I will postpone it for later. The docs >> patch is adjusted accordingly. >> > > This problem is not caused by this patch series. > But I think it's worth mentioning... > > It's really weird that some stack traces are not recorded > when CONFIG_KASAN=y. > > I made sure that: > - Stack Depot did not reach its limit > - the free path happen on CONFIG_KASAN=y too. > > I have no clue why this happen. > > # cat dentry/free_traces (CONFIG_KASAN=y) > 6585 <not-available> age=4294912647 pid=0 cpus=0 I think it's some kind of KASAN quarantining of freed objects, so they haven't been properly freed through the SLUB layer yet. > # cat dentry/free_traces (CONFIG_KASAN=n) > 1246 <not-available> age=4294906877 pid=0 cpus=0 > 379 __d_free+0x20/0x2c age=33/14225/14353 pid=0-122 cpus=0-3 > kmem_cache_free+0x1f4/0x21c > __d_free+0x20/0x2c > rcu_core+0x334/0x580 > rcu_core_si+0x14/0x20 > __do_softirq+0x12c/0x2a8 > > 2 dentry_free+0x58/0xb0 age=14101/14101/14101 pid=158 cpus=0 > kmem_cache_free+0x1f4/0x21c > dentry_free+0x58/0xb0 > __dentry_kill+0x18c/0x1d0 > dput+0x1c4/0x2fc > __fput+0xb0/0x230 > ____fput+0x14/0x20 > task_work_run+0x84/0x17c > do_notify_resume+0x208/0x1330 > el0_svc+0x6c/0x80 > el0t_64_sync_handler+0xa8/0x130 > el0t_64_sync+0x1a0/0x1a4 > > 1 dentry_free+0x58/0xb0 age=7678 pid=190 cpus=1 > kmem_cache_free+0x1f4/0x21c > dentry_free+0x58/0xb0 > __dentry_kill+0x18c/0x1d0 > dput+0x1c4/0x2fc > __fput+0xb0/0x230 > ____fput+0x14/0x20 > task_work_run+0x84/0x17c > do_exit+0x2dc/0x8e0 > do_group_exit+0x38/0xa4 > __wake_up_parent+0x0/0x34 > invoke_syscall+0x48/0x114 > el0_svc_common.constprop.0+0x44/0xfc > do_el0_svc+0x2c/0x94 > el0_svc+0x28/0x80 > el0t_64_sync_handler+0xa8/0x130 > el0t_64_sync+0x1a0/0x1a4
