Messages in this thread | | | From | Jirka Hladky <> | Date | Wed, 20 Apr 2022 10:02:20 +0200 | Subject | Re: PANIC: "Oops: 0000 [#1] PREEMPT SMP PTI" starting from 5.17 on dual socket Intel Xeon Gold servers |
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Hi Minchan,
have you heard back from the kernfs maintainers?
Thank you! Jirka
On Mon, Apr 4, 2022 at 7:41 PM Minchan Kim <minchan@kernel.org> wrote: > > On Fri, Apr 01, 2022 at 02:04:03PM +0200, Jirka Hladky wrote: > > > Could you decode exact source code line from the oops? > > > > Yes - please see below [1]. > > Thanks. > > > > > > I think it's fine to attach in the reply because kernel test bot > > > > OK. The reproducer is attached. Please unpack it and follow the > > instructions in the README file. [2] > > Unfortunately, I failed to run the script in my machine. > > > > > Thanks a lot for looking into it! > > Jirka > > > > [1] > > ============================================= > > Source code line numbers for the Oops message > > ============================================= > > > > 1) RIP: 0010:kernfs_remove+0x8/0x50: > > (gdb) l *kernfs_remove+0x8 > > 0xffffffff81418588 is in kernfs_remove (fs/kernfs/kernfs-internal.h:48). > > 43 * Return the kernfs_root @kn belongs to. > > 44 */ > > 45 static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn) > > 46 { > > 47 /* if parent exists, it's always a dir; otherwise, @sd > > is a dir */ > > 48 if (kn->parent) > > 49 kn = kn->parent; > > 50 return kn->dir.root; > > 51 } > > > > And here are source code lines from the 5 first functions in call trace: > > [ 8563.366280] Call Trace: > > [ 8563.366280] <TASK> > > [ 8563.366280] rdt_kill_sb+0x29d/0x350 > > [ 8563.366280] deactivate_locked_super+0x36/0xa0 > > [ 8563.366280] cleanup_mnt+0x131/0x190 > > [ 8563.366280] task_work_run+0x5c/0x90 > > [ 8563.366280] exit_to_user_mode_prepare+0x229/0x230 > > [ 8563.366280] syscall_exit_to_user_mode+0x18/0x40 > > [ 8563.366280] do_syscall_64+0x48/0x90 > > [ 8563.366280] entry_SYSCALL_64_after_hwframe+0x44/0xae > > > > 2)(gdb) l *rdt_kill_sb+0x29d > > 0xffffffff810506bd is in rdt_kill_sb > > (arch/x86/kernel/cpu/resctrl/rdtgroup.c:2442). > > 2437 /* Notify online CPUs to update per cpu storage and > > PQR_ASSOC MSR */ > > 2438 update_closid_rmid(cpu_online_mask, &rdtgroup_default); > > 2439 > > 2440 kernfs_remove(kn_info); > > 2441 kernfs_remove(kn_mongrp); > > 2442 kernfs_remove(kn_mondata); > > 2443 } > > > > 3)(gdb) l *deactivate_locked_super+0x36 > > 0xffffffff813650f6 is in deactivate_locked_super (fs/super.c:342). > > 337 /* > > 338 * Since list_lru_destroy() may sleep, we > > cannot call it from > > 339 * put_super(), where we hold the sb_lock. > > Therefore we destroy > > 340 * the lru lists right now. > > 341 */ > > 342 list_lru_destroy(&s->s_dentry_lru); > > 343 list_lru_destroy(&s->s_inode_lru); > > 344 > > 345 put_filesystem(fs); > > 346 put_super(s); > > > > 4) (gdb) l *cleanup_mnt+0x131 > > 0xffffffff813890a1 is in cleanup_mnt (fs/namespace.c:137). > > 132 return 0; > > 133 } > > 134 > > 135 static void mnt_free_id(struct mount *mnt) > > 136 { > > 137 ida_free(&mnt_id_ida, mnt->mnt_id); > > 138 } > > > > 5) (gdb) l *task_work_run+0x5c > > 0xffffffff8110620c is in task_work_run (./include/linux/sched.h:2017). > > 2012 > > 2013 DECLARE_STATIC_CALL(cond_resched, __cond_resched); > > 2014 > > 2015 static __always_inline int _cond_resched(void) > > 2016 { > > 2017 return static_call_mod(cond_resched)(); > > 2018 } > > > > 6) (gdb) l *exit_to_user_mode_prepare+0x229 > > 0xffffffff81176d19 is in exit_to_user_mode_prepare > > (./include/linux/tracehook.h:189). > > 184 * This barrier pairs with > > task_work_add()->set_notify_resume() after > > 185 * hlist_add_head(task->task_works); > > 186 */ > > 187 smp_mb__after_atomic(); > > 188 if (unlikely(current->task_works)) > > 189 task_work_run(); > > 190 > > 191 #ifdef CONFIG_KEYS_REQUEST_CACHE > > 192 if (unlikely(current->cached_requested_key)) { > > 193 key_put(current->cached_requested_key); > > > > [2] > > ============================================= > > Reproducer - README > > ============================================= > > > > 1) HW > > This issue seems to be platform specific. I was not able to reproduce > > it on AMD Zen and also not on Intel Ice Lake platform. > > I see the issue on dual socket Intel Skylake systems. Reproduced on a > > Supermicro Super Server/X11DDW-L with 2x Xeon Gold 6126 CPU. > > Based on your report, kernel was crashed due to kn_mondata was NULL > > rdt_kill_sb > rmdir_all_sub > .. > kernfs_remove(kn_mondata); > struct kernfs_root *root = kernfs_root(kn); <-- crashed > > > Before the my patch[1], it worked like this. > > rdt_kill_sb > rmdir_all_sub > .. > kernfs_remove(kn_mondata); > down_write(&kernfs_rwsem); > if (!kn) > return; > up_write(&kernfs_rwsem); > > IOW, before, kernfs_remove worked with NULL argument via just bailing > but with the my patch[1], it doesn't work any longer. > > It makes me have questions for kernfs maintainers: > > Should kernfs_remove API support NULL parameter? If so, can we support > it atomically without old global kernfs_rwsem? > > [1] 393c3714081a, kernfs: switch global kernfs_rwsem lock to per-fs lock >
-- -Jirka
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