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I saw the issues. It fails to mount in my case with panic trace. >>> >>> (Just to ensure that there is not anything else going on) Could you please confirm if the panic is from >>> mon_add_all_files()->mon_event_read()->mon_event_count()->__mon_event_count()->resctrl_arch_reset_rmid() >>> that creates the MBM event files during mount and then does the initial read of RMID to determine the >>> starting count? >> >> It happens just before that (at mbm_cntr_get). We have not allocated d->cntr_cfg for the counters. >> ===================Panic trace ================================= >> >> 349.330416] BUG: kernel NULL pointer dereference, address: 0000000000000008 >> [  349.338187] #PF: supervisor read access in kernel mode >> [  349.343914] #PF: error_code(0x0000) - not-present page >> [  349.349644] PGD 10419f067 P4D 0 >> [  349.353241] Oops: Oops: 0000 [#1] SMP NOPTI >> [  349.357905] CPU: 45 UID: 0 PID: 3449 Comm: mount Not tainted 6.18.0-rc1+ #120 PREEMPT(voluntary) >> [  349.367803] Hardware name: AMD Corporation PURICO/PURICO, BIOS RPUT1003E 12/11/2024 >> [  349.376334] RIP: 0010:mbm_cntr_get+0x56/0x90 >> [  349.381096] Code: 45 8d 41 fe 83 f8 01 77 3d 8b 7b 50 85 ff 7e 36 49 8b 84 24 f0 04 00 00 45 31 c0 eb 0d 41 83 c0 01 48 83 c0 10 44 39 c7 74 1c <48> 3b 50 08 75 ed 3b 08 75 e9 48 83 c4 10 44 89 c0 5b 41 5c 41 5d >> [  349.402037] RSP: 0018:ff56bba58655f958 EFLAGS: 00010246 >> [  349.407861] RAX: 0000000000000000 RBX: ffffffff9525b900 RCX: 0000000000000002 >> [  349.415818] RDX: ffffffff95d526a0 RSI: ff1f5d52517c1800 RDI: 0000000000000020 >> [  349.423774] RBP: ff56bba58655f980 R08: 0000000000000000 R09: 0000000000000001 >> [  349.431730] R10: ff1f5d52c616a6f0 R11: fffc6a2f046c3980 R12: ff1f5d52517c1800 >> [  349.439687] R13: 0000000000000001 R14: ffffffff95d526a0 R15: ffffffff9525b968 >> [  349.447635] FS:  00007f17926b7800(0000) GS:ff1f5d59d45ff000(0000) knlGS:0000000000000000 >> [  349.456659] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [  349.463064] CR2: 0000000000000008 CR3: 0000000147afe002 CR4: 0000000000771ef0 >> [  349.471022] PKRU: 55555554 >> [  349.474033] Call Trace: >> [  349.476755]  >> [  349.479091]  ? kernfs_add_one+0x114/0x170 >> [  349.483560]  rdtgroup_assign_cntr_event+0x9b/0xd0 >> [  349.488795]  rdtgroup_assign_cntrs+0xab/0xb0 >> [  349.493553]  rdt_get_tree+0x4be/0x770 >> [  349.497623]  vfs_get_tree+0x2e/0xf0 >> [  349.501508]  fc_mount+0x18/0x90 >> [  349.505007]  path_mount+0x360/0xc50 >> [  349.508884]  ? putname+0x68/0x80 >> [  349.512479]  __x64_sys_mount+0x124/0x150 >> [  349.516848]  x64_sys_call+0x2133/0x2190 >> [  349.521123]  do_syscall_64+0x74/0x970 >> >> ================================================================== > > Thank you for capturing this. This is a different trace but it confirms that it is the > same root cause. Specifically, event is enabled after the state it depends on is (not) allocated > during domain online. > Yes. Thanks Here is the changelog. x86,fs/resctrl: Fix BUG with mbm_event mode when MBM events are disabled The following BUG is encountered when mounting the resctrl filesystem after booting a system with X86_FEATURE_ABMC support and the kernel parameter 'rdt=!mbmtotal,!mbmlocal'. =========================================================================== [ 349.330416] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 349.338187] #PF: supervisor read access in kernel mode [ 349.343914] #PF: error_code(0x0000) - not-present page [ 349.349644] PGD 10419f067 P4D 0 [ 349.353241] Oops: Oops: 0000 [#1] SMP NOPTI [ 349.357905] CPU: 45 UID: 0 PID: 3449 Comm: mount Not tainted 6.18.0-rc1+ #120 PREEMPT(voluntary) [ 349.367803] Hardware name: AMD Corporation [ 349.376334] RIP: 0010:mbm_cntr_get+0x56/0x90 [ 349.381096] Code: 45 8d 41 fe 83 f8 01 77 3d 8b 7b 50 85 ff 7e 36 49 8b 84 24 f0 04 00 00 45 31 c0 eb 0d 41 83 c0 01 48 83 c0 10 44 39 c7 74 1c <48> 3b 50 08 75 ed 3b 08 75 e9 48 83 c4 10 44 89 c0 5b 41 5c 41 5d [ 349.402037] RSP: 0018:ff56bba58655f958 EFLAGS: 00010246 [ 349.407861] RAX: 0000000000000000 RBX: ffffffff9525b900 RCX: 0000000000000002 [ 349.415818] RDX: ffffffff95d526a0 RSI: ff1f5d52517c1800 RDI: 0000000000000020 [ 349.423774] RBP: ff56bba58655f980 R08: 0000000000000000 R09: 0000000000000001 [ 349.431730] R10: ff1f5d52c616a6f0 R11: fffc6a2f046c3980 R12: ff1f5d52517c1800 [ 349.439687] R13: 0000000000000001 R14: ffffffff95d526a0 R15: ffffffff9525b968 [ 349.447635] FS: 00007f17926b7800(0000) GS:ff1f5d59d45ff000(0000) knlGS:0000000000000000 [ 349.456659] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 349.463064] CR2: 0000000000000008 CR3: 0000000147afe002 CR4: 0000000000771ef0 [ 349.471022] PKRU: 55555554 [ 349.474033] Call Trace: [ 349.476755] [ 349.479091] ? kernfs_add_one+0x114/0x170 [ 349.483560] rdtgroup_assign_cntr_event+0x9b/0xd0 [ 349.488795] rdtgroup_assign_cntrs+0xab/0xb0 [ 349.493553] rdt_get_tree+0x4be/0x770 [ 349.497623] vfs_get_tree+0x2e/0xf0 [ 349.501508] fc_mount+0x18/0x90 [ 349.505007] path_mount+0x360/0xc50 [ 349.508884] ? putname+0x68/0x80 [ 349.512479] __x64_sys_mount+0x124/0x150 When mbm_event mode is enabled, it implicitly enables both MBM total and local events. However, specifying the kernel parameter "rdt=!mbmtotal,!mbmlocal" disables these events during resctrl initialization. As a result, related data structures, such as rdt_mon_domain::mbm_states, cntr_cfg, and rdt_hw_mon_domain::arch_mbm_states are not allocated. This leads to a BUG when the user attempts to mount the resctrl filesystem, which tries to access these un-allocated structures. Fix the issue by adding a dependency on X86_FEATURE_CQM_MBM_TOTAL and X86_FEATURE_CQM_MBM_LOCAL for X86_FEATURE_ABMC to be enabled. This is acceptable for now, as X86_FEATURE_ABMC currently implies support for MBM total and local events. However, this dependency should be revisited and removed in the future to decouple feature handling more cleanly. Fixes: 13390861b426e ("x86,fs/resctrl: Detect Assignable Bandwidth Monitoring feature details") Co-developed-by: Reinette Chatre Signed-off-by: Reinette Chatre Signed-off-by: Babu Moger ==================================================== thanks Babu