From: Li Rongqing <lirongqing@xxxxxxxxx> [ Upstream commit d6a2946a88f524a47cc9b79279667137899db807 ] msgctl10 of ltp triggers the following lockup When CONFIG_KASAN is enabled on large memory SMP systems, the pages initialization can take a long time, if msgctl10 requests a huge block memory, and it will block rcu scheduler, so release cpu actively. After adding schedule() in free_msg, free_msg can not be called when holding spinlock, so adding msg to a tmp list, and free it out of spinlock rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-1 rcu_node (CPUs 16-31): P32505 rcu: Tasks blocked on level-1 rcu_node (CPUs 48-63): P34978 rcu: (detected by 11, t=35024 jiffies, g=44237529, q=16542267) msgctl10 R running task 21608 32505 2794 0x00000082 Call Trace: preempt_schedule_irq+0x4c/0xb0 retint_kernel+0x1b/0x2d RIP: 0010:__is_insn_slot_addr+0xfb/0x250 Code: 82 1d 00 48 8b 9b 90 00 00 00 4c 89 f7 49 c1 ee 03 e8 59 83 1d 00 48 b8 00 00 00 00 00 fc ff df 4c 39 eb 48 89 9d 58 ff ff ff <41> c6 04 06 f8 74 66 4c 8d 75 98 4c 89 f1 48 c1 e9 03 48 01 c8 48 RSP: 0018:ffff88bce041f758 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffffffff8471bc50 RCX: ffffffff828a2a57 RDX: dffffc0000000000 RSI: dffffc0000000000 RDI: ffff88bce041f780 RBP: ffff88bce041f828 R08: ffffed15f3f4c5b3 R09: ffffed15f3f4c5b3 R10: 0000000000000001 R11: ffffed15f3f4c5b2 R12: 000000318aee9b73 R13: ffffffff8471bc50 R14: 1ffff1179c083ef0 R15: 1ffff1179c083eec kernel_text_address+0xc1/0x100 __kernel_text_address+0xe/0x30 unwind_get_return_address+0x2f/0x50 __save_stack_trace+0x92/0x100 create_object+0x380/0x650 __kmalloc+0x14c/0x2b0 load_msg+0x38/0x1a0 do_msgsnd+0x19e/0xcf0 do_syscall_64+0x117/0x400 entry_SYSCALL_64_after_hwframe+0x49/0xbe rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-1 rcu_node (CPUs 0-15): P32170 rcu: (detected by 14, t=35016 jiffies, g=44237525, q=12423063) msgctl10 R running task 21608 32170 32155 0x00000082 Call Trace: preempt_schedule_irq+0x4c/0xb0 retint_kernel+0x1b/0x2d RIP: 0010:lock_acquire+0x4d/0x340 Code: 48 81 ec c0 00 00 00 45 89 c6 4d 89 cf 48 8d 6c 24 20 48 89 3c 24 48 8d bb e4 0c 00 00 89 74 24 0c 48 c7 44 24 20 b3 8a b5 41 <48> c1 ed 03 48 c7 44 24 28 b4 25 18 84 48 c7 44 24 30 d0 54 7a 82 RSP: 0018:ffff88af83417738 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff88bd335f3080 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88bd335f3d64 RBP: ffff88af83417758 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffed13f3f745b2 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 is_bpf_text_address+0x32/0xe0 kernel_text_address+0xec/0x100 __kernel_text_address+0xe/0x30 unwind_get_return_address+0x2f/0x50 __save_stack_trace+0x92/0x100 save_stack+0x32/0xb0 __kasan_slab_free+0x130/0x180 kfree+0xfa/0x2d0 free_msg+0x24/0x50 do_msgrcv+0x508/0xe60 do_syscall_64+0x117/0x400 entry_SYSCALL_64_after_hwframe+0x49/0xbe Davidlohr said: "So after releasing the lock, the msg rbtree/list is empty and new calls will not see those in the newly populated tmp_msg list, and therefore they cannot access the delayed msg freeing pointers, which is good. Also the fact that the node_cache is now freed before the actual messages seems to be harmless as this is wanted for msg_insert() avoiding GFP_ATOMIC allocations, and after releasing the info->lock the thing is freed anyway so it should not change things" Link: http://lkml.kernel.org/r/1552029161-4957-1-git-send-email-lirongqing@xxxxxxxxx Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx> Signed-off-by: Zhang Yu <zhangyu31@xxxxxxxxx> Reviewed-by: Davidlohr Bueso <dbueso@xxxxxxx> Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- ipc/mqueue.c | 10 ++++++++-- ipc/msgutil.c | 6 ++++++ 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/ipc/mqueue.c b/ipc/mqueue.c index d240256263103..5c0ae912f2f25 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -374,7 +374,8 @@ static void mqueue_evict_inode(struct inode *inode) struct user_struct *user; unsigned long mq_bytes, mq_treesize; struct ipc_namespace *ipc_ns; - struct msg_msg *msg; + struct msg_msg *msg, *nmsg; + LIST_HEAD(tmp_msg); clear_inode(inode); @@ -385,10 +386,15 @@ static void mqueue_evict_inode(struct inode *inode) info = MQUEUE_I(inode); spin_lock(&info->lock); while ((msg = msg_get(info)) != NULL) - free_msg(msg); + list_add_tail(&msg->m_list, &tmp_msg); kfree(info->node_cache); spin_unlock(&info->lock); + list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) { + list_del(&msg->m_list); + free_msg(msg); + } + /* Total amount of bytes accounted for the mqueue */ mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) + min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) * diff --git a/ipc/msgutil.c b/ipc/msgutil.c index 84598025a6ade..e65593742e2be 100644 --- a/ipc/msgutil.c +++ b/ipc/msgutil.c @@ -18,6 +18,7 @@ #include <linux/utsname.h> #include <linux/proc_ns.h> #include <linux/uaccess.h> +#include <linux/sched.h> #include "util.h" @@ -64,6 +65,9 @@ static struct msg_msg *alloc_msg(size_t len) pseg = &msg->next; while (len > 0) { struct msg_msgseg *seg; + + cond_resched(); + alen = min(len, DATALEN_SEG); seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT); if (seg == NULL) @@ -176,6 +180,8 @@ void free_msg(struct msg_msg *msg) kfree(msg); while (seg != NULL) { struct msg_msgseg *tmp = seg->next; + + cond_resched(); kfree(seg); seg = tmp; } -- 2.20.1
