From 345daff2e994ee844d6a609c37f085695fbb4c4d Mon Sep 17 00:00:00 2001 From: Alexey Gladkov Date: Tue, 27 Jul 2021 17:24:18 +0200 Subject: ucounts: Fix race condition between alloc_ucounts and put_ucounts The race happens because put_ucounts() doesn't use spinlock and get_ucounts is not under spinlock: CPU0 CPU1 ---- ---- alloc_ucounts() put_ucounts() spin_lock_irq(&ucounts_lock); ucounts = find_ucounts(ns, uid, hashent); atomic_dec_and_test(&ucounts->count)) spin_unlock_irq(&ucounts_lock); spin_lock_irqsave(&ucounts_lock, flags); hlist_del_init(&ucounts->node); spin_unlock_irqrestore(&ucounts_lock, flags); kfree(ucounts); ucounts = get_ucounts(ucounts); ================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic_add_negative include/asm-generic/atomic-instrumented.h:556 [inline] BUG: KASAN: use-after-free in get_ucounts kernel/ucount.c:152 [inline] BUG: KASAN: use-after-free in get_ucounts kernel/ucount.c:150 [inline] BUG: KASAN: use-after-free in alloc_ucounts+0x19b/0x5b0 kernel/ucount.c:188 Write of size 4 at addr ffff88802821e41c by task syz-executor.4/16785 CPU: 1 PID: 16785 Comm: syz-executor.4 Not tainted 5.14.0-rc1-next-20210712-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:436 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_add_negative include/asm-generic/atomic-instrumented.h:556 [inline] get_ucounts kernel/ucount.c:152 [inline] get_ucounts kernel/ucount.c:150 [inline] alloc_ucounts+0x19b/0x5b0 kernel/ucount.c:188 set_cred_ucounts+0x171/0x3a0 kernel/cred.c:684 __sys_setuid+0x285/0x400 kernel/sys.c:623 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665d9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fde54097188 EFLAGS: 00000246 ORIG_RAX: 0000000000000069 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000000000ff RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffc8655740f R14: 00007fde54097300 R15: 0000000000022000 Allocated by task 16784: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522 kmalloc include/linux/slab.h:591 [inline] kzalloc include/linux/slab.h:721 [inline] alloc_ucounts+0x23d/0x5b0 kernel/ucount.c:169 set_cred_ucounts+0x171/0x3a0 kernel/cred.c:684 __sys_setuid+0x285/0x400 kernel/sys.c:623 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 16785: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:229 [inline] slab_free_hook mm/slub.c:1650 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1675 slab_free mm/slub.c:3235 [inline] kfree+0xeb/0x650 mm/slub.c:4295 put_ucounts kernel/ucount.c:200 [inline] put_ucounts+0x117/0x150 kernel/ucount.c:192 put_cred_rcu+0x27a/0x520 kernel/cred.c:124 rcu_do_batch kernel/rcu/tree.c:2550 [inline] rcu_core+0x7ab/0x1380 kernel/rcu/tree.c:2785 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 Last potentially related work creation: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348 insert_work+0x48/0x370 kernel/workqueue.c:1332 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498 queue_work_on+0xee/0x110 kernel/workqueue.c:1525 queue_work include/linux/workqueue.h:507 [inline] call_usermodehelper_exec+0x1f0/0x4c0 kernel/umh.c:435 kobject_uevent_env+0xf8f/0x1650 lib/kobject_uevent.c:618 netdev_queue_add_kobject net/core/net-sysfs.c:1621 [inline] netdev_queue_update_kobjects+0x374/0x450 net/core/net-sysfs.c:1655 register_queue_kobjects net/core/net-sysfs.c:1716 [inline] netdev_register_kobject+0x35a/0x430 net/core/net-sysfs.c:1959 register_netdevice+0xd33/0x1500 net/core/dev.c:10331 nsim_init_netdevsim drivers/net/netdevsim/netdev.c:317 [inline] nsim_create+0x381/0x4d0 drivers/net/netdevsim/netdev.c:364 __nsim_dev_port_add+0x32e/0x830 drivers/net/netdevsim/dev.c:1295 nsim_dev_port_add_all+0x53/0x150 drivers/net/netdevsim/dev.c:1355 nsim_dev_probe+0xcb5/0x1190 drivers/net/netdevsim/dev.c:1496 call_driver_probe drivers/base/dd.c:517 [inline] really_probe+0x23c/0xcd0 drivers/base/dd.c:595 __driver_probe_device+0x338/0x4d0 drivers/base/dd.c:747 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:777 __device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:894 bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427 __device_attach+0x228/0x4a0 drivers/base/dd.c:965 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487 device_add+0xc2f/0x2180 drivers/base/core.c:3356 nsim_bus_dev_new drivers/net/netdevsim/bus.c:431 [inline] new_device_store+0x436/0x710 drivers/net/netdevsim/bus.c:298 bus_attr_store+0x72/0xa0 drivers/base/bus.c:122 sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2152 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x75a/0xa40 fs/read_write.c:605 ksys_write+0x12d/0x250 fs/read_write.c:658 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Second to last potentially related work creation: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348 insert_work+0x48/0x370 kernel/workqueue.c:1332 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498 queue_work_on+0xee/0x110 kernel/workqueue.c:1525 queue_work include/linux/workqueue.h:507 [inline] call_usermodehelper_exec+0x1f0/0x4c0 kernel/umh.c:435 kobject_uevent_env+0xf8f/0x1650 lib/kobject_uevent.c:618 kobject_synth_uevent+0x701/0x850 lib/kobject_uevent.c:208 uevent_store+0x20/0x50 drivers/base/core.c:2371 dev_attr_store+0x50/0x80 drivers/base/core.c:2072 sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296 call_write_iter include/linux/fs.h:2152 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x75a/0xa40 fs/read_write.c:605 ksys_write+0x12d/0x250 fs/read_write.c:658 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88802821e400 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 28 bytes inside of 192-byte region [ffff88802821e400, ffff88802821e4c0) The buggy address belongs to the page: page:ffffea0000a08780 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2821e flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888010841a00 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, ts 12874702440, free_ts 12637793385 prep_new_page mm/page_alloc.c:2433 [inline] get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4166 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5374 alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2119 alloc_pages+0x238/0x2a0 mm/mempolicy.c:2242 alloc_slab_page mm/slub.c:1713 [inline] allocate_slab+0x32b/0x4c0 mm/slub.c:1853 new_slab mm/slub.c:1916 [inline] new_slab_objects mm/slub.c:2662 [inline] ___slab_alloc+0x4ba/0x820 mm/slub.c:2825 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2865 slab_alloc_node mm/slub.c:2947 [inline] slab_alloc mm/slub.c:2989 [inline] __kmalloc+0x312/0x330 mm/slub.c:4133 kmalloc include/linux/slab.h:596 [inline] kzalloc include/linux/slab.h:721 [inline] __register_sysctl_table+0x112/0x1090 fs/proc/proc_sysctl.c:1318 rds_tcp_init_net+0x1db/0x4f0 net/rds/tcp.c:551 ops_init+0xaf/0x470 net/core/net_namespace.c:140 __register_pernet_operations net/core/net_namespace.c:1137 [inline] register_pernet_operations+0x35a/0x850 net/core/net_namespace.c:1214 register_pernet_device+0x26/0x70 net/core/net_namespace.c:1301 rds_tcp_init+0x77/0xe0 net/rds/tcp.c:717 do_one_initcall+0x103/0x650 init/main.c:1285 do_initcall_level init/main.c:1360 [inline] do_initcalls init/main.c:1376 [inline] do_basic_setup init/main.c:1396 [inline] kernel_init_freeable+0x6b8/0x741 init/main.c:1598 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1343 [inline] free_pcp_prepare+0x312/0x7d0 mm/page_alloc.c:1394 free_unref_page_prepare mm/page_alloc.c:3329 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3408 __vunmap+0x783/0xb70 mm/vmalloc.c:2587 free_work+0x58/0x70 mm/vmalloc.c:82 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff88802821e300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88802821e380: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc >ffff88802821e400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802821e480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88802821e500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== - The race fix has two parts. * Changing the code to guarantee that ucounts->count is only decremented when ucounts_lock is held. This guarantees that find_ucounts will never find a structure with a zero reference count. * Changing alloc_ucounts to increment ucounts->count while ucounts_lock is held. This guarantees the reference count on the found data structure will not be decremented to zero (and the data structure freed) before the reference count is incremented. -- Eric Biederman Reported-by: syzbot+01985d7909f9468f013c@syzkaller.appspotmail.com Reported-by: syzbot+59dd63761094a80ad06d@syzkaller.appspotmail.com Reported-by: syzbot+6cd79f45bb8fa1c9eeae@syzkaller.appspotmail.com Reported-by: syzbot+b6e65bd125a05f803d6b@syzkaller.appspotmail.com Fixes: b6c336528926 ("Use atomic_t for ucounts reference counting") Cc: Hillf Danton Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/7b2ace1759b281cdd2d66101d6b305deef722efb.1627397820.git.legion@kernel.org Signed-off-by: Eric W. Biederman --- kernel/ucount.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/ucount.c b/kernel/ucount.c index 87799e2379bd..77be3bbe3cc4 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -160,6 +160,7 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) { struct hlist_head *hashent = ucounts_hashentry(ns, uid); struct ucounts *ucounts, *new; + long overflow; spin_lock_irq(&ucounts_lock); ucounts = find_ucounts(ns, uid, hashent); @@ -184,8 +185,12 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) return new; } } + overflow = atomic_add_negative(1, &ucounts->count); spin_unlock_irq(&ucounts_lock); - ucounts = get_ucounts(ucounts); + if (overflow) { + put_ucounts(ucounts); + return NULL; + } return ucounts; } @@ -193,8 +198,7 @@ void put_ucounts(struct ucounts *ucounts) { unsigned long flags; - if (atomic_dec_and_test(&ucounts->count)) { - spin_lock_irqsave(&ucounts_lock, flags); + if (atomic_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, flags)) { hlist_del_init(&ucounts->node); spin_unlock_irqrestore(&ucounts_lock, flags); kfree(ucounts); -- cgit v1.3-14-g43fede From ff41c28c4b54052942180d8b3f49e75f1445135a Mon Sep 17 00:00:00 2001 From: Kamal Agrawal Date: Fri, 30 Jul 2021 18:53:06 +0530 Subject: tracing: Fix NULL pointer dereference in start_creating The event_trace_add_tracer() can fail. In this case, it leads to a crash in start_creating with below call stack. Handle the error scenario properly in trace_array_create_dir. Call trace: down_write+0x7c/0x204 start_creating.25017+0x6c/0x194 tracefs_create_file+0xc4/0x2b4 init_tracer_tracefs+0x5c/0x940 trace_array_create_dir+0x58/0xb4 trace_array_create+0x1bc/0x2b8 trace_array_get_by_name+0xdc/0x18c Link: https://lkml.kernel.org/r/1627651386-21315-1-git-send-email-kamaagra@codeaurora.org Cc: stable@vger.kernel.org Fixes: 4114fbfd02f1 ("tracing: Enable creating new instance early boot") Signed-off-by: Kamal Agrawal Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c59dd35a6da5..33899a71fdc1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9135,8 +9135,10 @@ static int trace_array_create_dir(struct trace_array *tr) return -EINVAL; ret = event_trace_add_tracer(tr->dir, tr); - if (ret) + if (ret) { tracefs_remove(tr->dir); + return ret; + } init_tracer_tracefs(tr, tr->dir); __update_tracer_options(tr); -- cgit v1.3-14-g43fede From 2c05caa7ba8803209769b9e4fe02c38d77ae88d0 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Fri, 30 Jul 2021 17:19:51 -0400 Subject: tracing / histogram: Give calculation hist_fields a size When working on my user space applications, I found a bug in the synthetic event code where the automated synthetic event field was not matching the event field calculation it was attached to. Looking deeper into it, it was because the calculation hist_field was not given a size. The synthetic event fields are matched to their hist_fields either by having the field have an identical string type, or if that does not match, then the size and signed values are used to match the fields. The problem arose when I tried to match a calculation where the fields were "unsigned int". My tool created a synthetic event of type "u32". But it failed to match. The string was: diff=field1-field2:onmatch(event).trace(synth,$diff) Adding debugging into the kernel, I found that the size of "diff" was 0. And since it was given "unsigned int" as a type, the histogram fallback code used size and signed. The signed matched, but the size of u32 (4) did not match zero, and the event failed to be created. This can be worse if the field you want to match is not one of the acceptable fields for a synthetic event. As event fields can have any type that is supported in Linux, this can cause an issue. For example, if a type is an enum. Then there's no way to use that with any calculations. Have the calculation field simply take on the size of what it is calculating. Link: https://lkml.kernel.org/r/20210730171951.59c7743f@oasis.local.home Cc: Tom Zanussi Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Ingo Molnar Cc: Andrew Morton Cc: stable@vger.kernel.org Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_hist.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 34325f41ebc0..362db9b81b8d 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -2287,6 +2287,10 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data, expr->operands[0] = operand1; expr->operands[1] = operand2; + + /* The operand sizes should be the same, so just pick one */ + expr->size = operand1->size; + expr->operator = field_op; expr->name = expr_str(expr, 0); expr->type = kstrdup(operand1->type, GFP_KERNEL); -- cgit v1.3-14-g43fede From a9d10ca4986571bffc19778742d508cc8dd13e02 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 28 Jul 2021 07:55:43 +0900 Subject: tracing: Reject string operand in the histogram expression Since the string type can not be the target of the addition / subtraction operation, it must be rejected. Without this fix, the string type silently converted to digits. Link: https://lkml.kernel.org/r/162742654278.290973.1523000673366456634.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers") Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events_hist.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 362db9b81b8d..949ef09dc537 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -65,7 +65,8 @@ C(INVALID_SORT_MODIFIER,"Invalid sort modifier"), \ C(EMPTY_SORT_FIELD, "Empty sort field"), \ C(TOO_MANY_SORT_FIELDS, "Too many sort fields (Max = 2)"), \ - C(INVALID_SORT_FIELD, "Sort field must be a key or a val"), + C(INVALID_SORT_FIELD, "Sort field must be a key or a val"), \ + C(INVALID_STR_OPERAND, "String type can not be an operand in expression"), #undef C #define C(a, b) HIST_ERR_##a @@ -2156,6 +2157,13 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data, ret = PTR_ERR(operand1); goto free; } + if (operand1->flags & HIST_FIELD_FL_STRING) { + /* String type can not be the operand of unary operator. */ + hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(str)); + destroy_hist_field(operand1, 0); + ret = -EINVAL; + goto free; + } expr->flags |= operand1->flags & (HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS); @@ -2257,6 +2265,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data, operand1 = NULL; goto free; } + if (operand1->flags & HIST_FIELD_FL_STRING) { + hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(operand1_str)); + ret = -EINVAL; + goto free; + } /* rest of string could be another expression e.g. b+c in a+b+c */ operand_flags = 0; @@ -2266,6 +2279,11 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data, operand2 = NULL; goto free; } + if (operand2->flags & HIST_FIELD_FL_STRING) { + hist_err(file->tr, HIST_ERR_INVALID_STR_OPERAND, errpos(str)); + ret = -EINVAL; + goto free; + } ret = check_expr_operands(file->tr, operand1, operand2); if (ret) -- cgit v1.3-14-g43fede From 51397dc6f283bb570e1cf8226017d300d8ea1f5b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 4 Aug 2021 14:18:48 -0400 Subject: tracing: Quiet smp_processor_id() use in preemptable warning in hwlat The hardware latency detector (hwlat) has a mode that it runs one thread across CPUs. The logic to move from the currently running CPU to the next one in the list does a smp_processor_id() to find where it currently is. Unfortunately, it's done with preemption enabled, and this triggers a warning for using smp_processor_id() in a preempt enabled section. As it is only using smp_processor_id() to get information on where it currently is in order to simply move it to the next CPU, it doesn't really care if it got moved in the mean time. It will simply balance out later if such a case arises. Switch smp_processor_id() to raw_smp_processor_id() to quiet that warning. Link: https://lkml.kernel.org/r/20210804141848.79edadc0@oasis.local.home Acked-by: Daniel Bristot de Oliveira Fixes: 8fa826b7344d ("trace/hwlat: Implement the mode config option") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_hwlat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c index a6c0cdaf4b87..14f46aae1981 100644 --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -327,7 +327,7 @@ static void move_to_next_cpu(void) get_online_cpus(); cpumask_and(current_mask, cpu_online_mask, tr->tracing_cpumask); - next_cpu = cpumask_next(smp_processor_id(), current_mask); + next_cpu = cpumask_next(raw_smp_processor_id(), current_mask); put_online_cpus(); if (next_cpu >= nr_cpu_ids) -- cgit v1.3-14-g43fede