On Mon, Jan 18, 2016 at 02:08:15PM +0100, Dmitry Vyukov wrote:
> Hello,
>
> While running syzkaller fuzzer I've hit the following report.
>
> Looks like cause by the recent commit
> e9b61f19858a5d6c42ce2298cf138279375d0d9b "thp: reintroduce
> split_huge_page()".
>
> ======================================================
> [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ]
> 4.4.0+ #259 Tainted: G W
> ------------------------------------------------------
> syz-executor/18183 [HC0[0]:SC0[2]:HE0:SE0] is trying to acquire:
> (split_queue_lock){+.+...}, at: [<ffffffff817847d4>]
> free_transhuge_page+0x24/0x90 mm/huge_memory.c:3436
>
> and this task is already holding:
> (slock-AF_INET){+.-...}, at: [< inline >] spin_lock_bh
> include/linux/spinlock.h:307
> (slock-AF_INET){+.-...}, at: [<ffffffff851c4fe5>]
> lock_sock_fast+0x45/0x120 net/core/sock.c:2462
> which would create a new lock dependency:
> (slock-AF_INET){+.-...} -> (split_queue_lock){+.+...}
>
> but this new dependency connects a SOFTIRQ-irq-safe lock:
> (slock-AF_INET){+.-...}
> ... which became SOFTIRQ-irq-safe at:
> [< inline >] mark_irqflags kernel/locking/lockdep.c:2799
> [<ffffffff81454718>] __lock_acquire+0xfd8/0x4700 kernel/locking/lockdep.c:3162
> [<ffffffff8145a28c>] lock_acquire+0x1dc/0x430 kernel/locking/lockdep.c:3585
> [< inline >] __raw_spin_lock include/linux/spinlock_api_smp.h:144
> [<ffffffff863248d3>] _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151
> [< inline >] spin_lock include/linux/spinlock.h:302
> [<ffffffff855e3df1>] udp_queue_rcv_skb+0x781/0x1550 net/ipv4/udp.c:1680
> [<ffffffff855e4c10>] flush_stack+0x50/0x330 net/ipv6/udp.c:799
> [<ffffffff855e5584>] __udp4_lib_mcast_deliver+0x694/0x7f0 net/ipv4/udp.c:1798
> [<ffffffff855e6ebc>] __udp4_lib_rcv+0x17dc/0x23e0 net/ipv4/udp.c:1888
> [<ffffffff855e9021>] udp_rcv+0x21/0x30 net/ipv4/udp.c:2108
> [<ffffffff85513b33>] ip_local_deliver_finish+0x2b3/0xa50
> net/ipv4/ip_input.c:216
> [< inline >] NF_HOOK_THRESH include/linux/netfilter.h:226
> [< inline >] NF_HOOK include/linux/netfilter.h:249
> [<ffffffff855149d4>] ip_local_deliver+0x1c4/0x2f0 net/ipv4/ip_input.c:257
> [< inline >] dst_input include/net/dst.h:498
> [<ffffffff8551273c>] ip_rcv_finish+0x5ec/0x1730 net/ipv4/ip_input.c:365
> [< inline >] NF_HOOK_THRESH include/linux/netfilter.h:226
> [< inline >] NF_HOOK include/linux/netfilter.h:249
> [<ffffffff85515463>] ip_rcv+0x963/0x1080 net/ipv4/ip_input.c:455
> [<ffffffff8521b410>] __netif_receive_skb_core+0x1620/0x2f80
> net/core/dev.c:4154
> [<ffffffff8521cd9a>] __netif_receive_skb+0x2a/0x160 net/core/dev.c:4189
> [<ffffffff85220795>] netif_receive_skb_internal+0x1b5/0x390
> net/core/dev.c:4217
> [< inline >] napi_skb_finish net/core/dev.c:4542
> [<ffffffff85224c9d>] napi_gro_receive+0x2bd/0x3c0 net/core/dev.c:4572
> [<ffffffff83a2f142>] e1000_clean_rx_irq+0x4e2/0x1100
> drivers/net/ethernet/intel/e1000e/netdev.c:1038
> [<ffffffff83a2c1f8>] e1000_clean+0xa08/0x24a0
> drivers/net/ethernet/intel/e1000/e1000_main.c:3819
> [< inline >] napi_poll net/core/dev.c:5074
> [<ffffffff8522285b>] net_rx_action+0x7eb/0xdf0 net/core/dev.c:5139
> [<ffffffff81361c0a>] __do_softirq+0x26a/0x920 kernel/softirq.c:273
> [< inline >] invoke_softirq kernel/softirq.c:350
> [<ffffffff8136264f>] irq_exit+0x18f/0x1d0 kernel/softirq.c:391
> [< inline >] exiting_irq ./arch/x86/include/asm/apic.h:659
> [<ffffffff811a9a66>] do_IRQ+0x86/0x1a0 arch/x86/kernel/irq.c:252
> [<ffffffff863264cc>] ret_from_intr+0x0/0x20 arch/x86/entry/entry_64.S:520
> [< inline >] arch_safe_halt ./arch/x86/include/asm/paravirt.h:117
> [<ffffffff811bdd42>] default_idle+0x52/0x2e0 arch/x86/kernel/process.c:304
> [<ffffffff811bf37a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:295
> [<ffffffff81439f48>] default_idle_call+0x48/0xa0 kernel/sched/idle.c:92
> [< inline >] cpuidle_idle_call kernel/sched/idle.c:156
> [< inline >] cpu_idle_loop kernel/sched/idle.c:252
> [<ffffffff8143a604>] cpu_startup_entry+0x554/0x710 kernel/sched/idle.c:300
> [<ffffffff86301262>] rest_init+0x192/0x1a0 init/main.c:412
> [<ffffffff882fa780>] start_kernel+0x678/0x69e init/main.c:683
> [<ffffffff882f9342>] x86_64_start_reservations+0x2a/0x2c
> arch/x86/kernel/head64.c:195
> [<ffffffff882f949c>] x86_64_start_kernel+0x158/0x167
> arch/x86/kernel/head64.c:184
>
> to a SOFTIRQ-irq-unsafe lock:
> (split_queue_lock){+.+...}
> ... which became SOFTIRQ-irq-unsafe at:
> ... [< inline >] mark_irqflags kernel/locking/lockdep.c:2817
> ... [<ffffffff81454bae>] __lock_acquire+0x146e/0x4700
> kernel/locking/lockdep.c:3162
> [<ffffffff8145a28c>] lock_acquire+0x1dc/0x430 kernel/locking/lockdep.c:3585
> [< inline >] __raw_spin_lock include/linux/spinlock_api_smp.h:144
> [<ffffffff863248d3>] _raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151
> [< inline >] spin_lock include/linux/spinlock.h:302
> [<ffffffff81782320>] split_huge_page_to_list+0xcc0/0x1c50
> mm/huge_memory.c:3399
> [< inline >] split_huge_page include/linux/huge_mm.h:99
> [<ffffffff8174a4e8>] queue_pages_pte_range+0xa38/0xef0 mm/mempolicy.c:507
> [< inline >] walk_pmd_range mm/pagewalk.c:50
> [< inline >] walk_pud_range mm/pagewalk.c:90
> [< inline >] walk_pgd_range mm/pagewalk.c:116
> [<ffffffff8171d4f3>] __walk_page_range+0x653/0xcd0 mm/pagewalk.c:204
> [<ffffffff8171dc6e>] walk_page_range+0xfe/0x2b0 mm/pagewalk.c:281
> [<ffffffff81746e7b>] queue_pages_range+0xfb/0x130 mm/mempolicy.c:687
> [< inline >] migrate_to_node mm/mempolicy.c:1004
> [<ffffffff8174c340>] do_migrate_pages+0x370/0x4e0 mm/mempolicy.c:1109
> [< inline >] SYSC_migrate_pages mm/mempolicy.c:1453
> [<ffffffff8174cc10>] SyS_migrate_pages+0x640/0x730 mm/mempolicy.c:1374
> [<ffffffff863259b6>] entry_SYSCALL_64_fastpath+0x16/0x7a
> arch/x86/entry/entry_64.S:185
>
> other info that might help us debug this:
>
> Possible interrupt unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(split_queue_lock);
> local_irq_disable();
> lock(slock-AF_INET);
> lock(split_queue_lock);
> <Interrupt>
> lock(slock-AF_INET);
Thanks for report.
I think this should fix the issue:
>From 10859758dadfa249616870f63c1636ec9857c501 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Mon, 18 Jan 2016 16:28:12 +0300
Subject: [PATCH] thp: fix interrupt unsafe locking in split_huge_page()
split_queue_lock can be taken from interrupt context in some cases, but
I forgot to convert locking in split_huge_page() to interrupt-safe
primitives.
Let's fix this.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
---
mm/huge_memory.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 50342eff7960..21fda6a10e89 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3357,6 +3357,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
struct anon_vma *anon_vma;
int count, mapcount, ret;
bool mlocked;
+ unsigned long flags;
VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
VM_BUG_ON_PAGE(!PageAnon(page), page);
@@ -3396,7 +3397,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
lru_add_drain();
/* Prevent deferred_split_scan() touching ->_count */
- spin_lock(&split_queue_lock);
+ spin_lock_irqsave(&split_queue_lock, flags);
count = page_count(head);
mapcount = total_mapcount(head);
if (!mapcount && count == 1) {
@@ -3404,11 +3405,11 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
split_queue_len--;
list_del(page_deferred_list(head));
}
- spin_unlock(&split_queue_lock);
+ spin_unlock_irqrestore(&split_queue_lock, flags);
__split_huge_page(page, list);
ret = 0;
} else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
- spin_unlock(&split_queue_lock);
+ spin_unlock_irqrestore(&split_queue_lock, flags);
pr_alert("total_mapcount: %u, page_count(): %u\n",
mapcount, count);
if (PageTail(page))
@@ -3416,7 +3417,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
dump_page(page, "total_mapcount(head) > 0");
BUG();
} else {
- spin_unlock(&split_queue_lock);
+ spin_unlock_irqrestore(&split_queue_lock, flags);
unfreeze_page(anon_vma, head);
ret = -EBUSY;
}
--
Kirill A. Shutemov
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