From: Pasi Sjöholm <[email protected]> It is possible to get kernel in deadlock-state if swap_lock is not locked with spin_lock_bh by calling si_swapinfo() simultaneously through timer_function and registered vm shinker callback-function.
BUG: spinlock recursion on CPU#0, main/2447 lock: swap_lock+0x0/0x10, .magic: dead4ead, .owner: main/2447, .owner_cpu: 0 [<c010b938>] (unwind_backtrace+0x0/0x11c) from [<c03e9be0>] (do_raw_spin_lock+0x48/0x154) [<c03e9be0>] (do_raw_spin_lock+0x48/0x154) from [<c0226e10>] (si_swapinfo+0x10/0x90) [<c0226e10>] (si_swapinfo+0x10/0x90) from [<c04d7e18>] (timer_function+0x24/0x258) [<c04d7e18>] (timer_function+0x24/0x258) from [<c0182a10>] (run_timer_softirq+0x27c/0x3c0) [<c0182a10>] (run_timer_softirq+0x27c/0x3c0) from [<c017bd10>] (__do_softirq+0x12c/0x268) [<c017bd10>] (__do_softirq+0x12c/0x268) from [<c017c25c>] (irq_exit+0x48/0xa0) [<c017c25c>] (irq_exit+0x48/0xa0) from [<c01066a4>] (handle_IRQ+0x80/0xc0) [<c01066a4>] (handle_IRQ+0x80/0xc0) from [<c0100474>] (gic_handle_irq+0x90/0x10c) [<c0100474>] (gic_handle_irq+0x90/0x10c) from [<c08a9500>] (__irq_svc+0x40/0x70) Exception stack(0xd3425a58 to 0xd3425aa0) 5a40: c20f628000000040 5a60: 0000005300000001c20f628000000bc5c0efb6c8c10b8be0000000d400000001 5a80: d3425bb40000000000000000d3425aa0c0228820c022820020000113ffffffff [<c08a9500>] (__irq_svc+0x40/0x70) from [<c0228200>] (scan_swap_map+0x14/0x518) [<c0228200>] (scan_swap_map+0x14/0x518) from [<c0228820>] (get_swap_page+0x98/0x108) [<c0228820>] (get_swap_page+0x98/0x108) from [<c0226400>] (add_to_swap+0x20/0x74) [<c0226400>] (add_to_swap+0x20/0x74) from [<c0208090>] (shrink_page_list+0x234/0x8a0) [<c0208090>] (shrink_page_list+0x234/0x8a0) from [<c0208b14>] (shrink_inactive_list+0x214/0x4c4) [<c0208b14>] (shrink_inactive_list+0x214/0x4c4) from [<c020919c>] (shrink_mem_cgroup_zone+0x3d8/0x534) Signed-off-by: Pasi Sjöholm <[email protected]> --- mm/swapfile.c | 54 +++++++++++++++++++++++++++--------------------------- 1 file changed, 27 insertions(+), 27 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 63f55cc..b00a55e 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -993,7 +993,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) if (device) bdev = bdget(device); - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); for (type = 0; type < nr_swapfiles; type++) { struct swap_info_struct *sis = swap_info[type]; @@ -1004,7 +1004,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) if (bdev_p) *bdev_p = bdgrab(sis->bdev); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); return type; } if (bdev == sis->bdev) { @@ -1014,13 +1014,13 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) if (bdev_p) *bdev_p = bdgrab(sis->bdev); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); bdput(bdev); return type; } } } - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); if (bdev) bdput(bdev); @@ -1052,7 +1052,7 @@ unsigned int count_swap_pages(int type, int free) { unsigned int n = 0; - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); if ((unsigned int)type < nr_swapfiles) { struct swap_info_struct *sis = swap_info[type]; @@ -1064,7 +1064,7 @@ unsigned int count_swap_pages(int type, int free) } spin_unlock(&sis->lock); } - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); return n; } #endif /* CONFIG_HIBERNATION */ @@ -1783,20 +1783,20 @@ static void enable_swap_info(struct swap_info_struct *p, int prio, unsigned long *frontswap_map) { frontswap_init(p->type, frontswap_map); - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); spin_lock(&p->lock); _enable_swap_info(p, prio, swap_map, cluster_info); spin_unlock(&p->lock); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); } static void reinsert_swap_info(struct swap_info_struct *p) { - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); spin_lock(&p->lock); _enable_swap_info(p, p->prio, p->swap_map, p->cluster_info); spin_unlock(&p->lock); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); } SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) @@ -1827,7 +1827,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) goto out; mapping = victim->f_mapping; - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); plist_for_each_entry(p, &swap_active_head, list) { if (p->flags & SWP_WRITEOK) { if (p->swap_file->f_mapping == mapping) { @@ -1838,14 +1838,14 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) } if (!found) { err = -EINVAL; - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); goto out_dput; } if (!security_vm_enough_memory_mm(current->mm, p->pages)) vm_unacct_memory(p->pages); else { err = -ENOMEM; - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); goto out_dput; } spin_lock(&swap_avail_lock); @@ -1867,7 +1867,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) total_swap_pages -= p->pages; p->flags &= ~SWP_WRITEOK; spin_unlock(&p->lock); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); set_current_oom_origin(); err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ @@ -1886,7 +1886,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) free_swap_count_continuations(p); mutex_lock(&swapon_mutex); - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); spin_lock(&p->lock); drain_mmlist(); @@ -1894,9 +1894,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) p->highest_bit = 0; /* cuts scans short */ while (p->flags >= SWP_SCANNING) { spin_unlock(&p->lock); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); schedule_timeout_uninterruptible(1); - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); spin_lock(&p->lock); } @@ -1910,7 +1910,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) p->cluster_info = NULL; frontswap_map = frontswap_map_get(p); spin_unlock(&p->lock); - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); frontswap_invalidate_area(p->type); frontswap_map_set(p, NULL); mutex_unlock(&swapon_mutex); @@ -1939,9 +1939,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) * can reuse this swap_info in alloc_swap_info() safely. It is ok to * not hold p->lock after we cleared its SWP_WRITEOK. */ - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); p->flags = 0; - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); err = 0; atomic_inc(&proc_poll_event); @@ -2098,13 +2098,13 @@ static struct swap_info_struct *alloc_swap_info(void) if (!p) return ERR_PTR(-ENOMEM); - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); for (type = 0; type < nr_swapfiles; type++) { if (!(swap_info[type]->flags & SWP_USED)) break; } if (type >= MAX_SWAPFILES) { - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); kfree(p); return ERR_PTR(-EPERM); } @@ -2130,7 +2130,7 @@ static struct swap_info_struct *alloc_swap_info(void) plist_node_init(&p->list, 0); plist_node_init(&p->avail_list, 0); p->flags = SWP_USED; - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); spin_lock_init(&p->lock); return p; @@ -2536,10 +2536,10 @@ bad_swap: } destroy_swap_extents(p); swap_cgroup_swapoff(p->type); - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); p->swap_file = NULL; p->flags = 0; - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); vfree(swap_map); vfree(cluster_info); if (swap_file) { @@ -2566,7 +2566,7 @@ void si_swapinfo(struct sysinfo *val) unsigned int type; unsigned long nr_to_be_unused = 0; - spin_lock(&swap_lock); + spin_lock_bh(&swap_lock); for (type = 0; type < nr_swapfiles; type++) { struct swap_info_struct *si = swap_info[type]; @@ -2575,7 +2575,7 @@ void si_swapinfo(struct sysinfo *val) } val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; val->totalswap = total_swap_pages + nr_to_be_unused; - spin_unlock(&swap_lock); + spin_unlock_bh(&swap_lock); } /* -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
