From: Joern Engel <joern@xxxxxxxxx> Mapping large memory spaces can be slow and prevent high-priority realtime threads from preempting lower-priority threads for a long time. In my case it was a 256GB mapping causing at least 950ms scheduler delay. Problem detection is ratelimited and depends on interrupts happening at the right time, so actual delay is likely worse. ------------[ cut here ]------------ WARNING: at arch/x86/kernel/irq.c:182 do_IRQ+0x126/0x140() Thread not rescheduled for 36 jiffies CPU: 14 PID: 6684 Comm: foo Tainted: G O 3.10.59+ 0000000000000009 ffff883f7fbc3ee0 ffffffff8163a12c ffff883f7fbc3f18 ffffffff8103f131 ffff887f48275ac0 0000000000000012 000000000000007c 0000000000000000 ffff887f5bc11fd8 ffff883f7fbc3f78 ffffffff8103f19c Call Trace: <IRQ> [<ffffffff8163a12c>] dump_stack+0x19/0x1b [<ffffffff8103f131>] warn_slowpath_common+0x61/0x80 [<ffffffff8103f19c>] warn_slowpath_fmt+0x4c/0x50 [<ffffffff810bd917>] ? rcu_irq_exit+0x77/0xc0 [<ffffffff8164a556>] do_IRQ+0x126/0x140 [<ffffffff816407ef>] common_interrupt+0x6f/0x6f <EOI> [<ffffffff810fde68>] ? set_pageblock_migratetype+0x28/0x30 [<ffffffff8126da37>] ? clear_page_c_e+0x7/0x10 [<ffffffff811004b3>] ? get_page_from_freelist+0x5b3/0x880 [<ffffffff81100863>] __alloc_pages_nodemask+0xe3/0x810 [<ffffffff8126f48b>] ? trace_hardirqs_on_thunk+0x3a/0x3c [<ffffffff81138206>] alloc_pages_current+0x86/0x120 [<ffffffff810fc02e>] __get_free_pages+0xe/0x50 [<ffffffff81034e85>] pte_alloc_one_kernel+0x15/0x20 [<ffffffff8111b6cd>] __pte_alloc_kernel+0x1d/0xf0 [<ffffffff8126531c>] ioremap_page_range+0x2cc/0x320 [<ffffffff81031619>] __ioremap_caller+0x1e9/0x2b0 [<ffffffff810316f7>] ioremap_nocache+0x17/0x20 [<ffffffff81275b45>] pci_iomap+0x55/0xb0 [<ffffffffa007f29a>] vfio_pci_mmap+0x1ea/0x210 [vfio_pci] [<ffffffffa0025173>] vfio_device_fops_mmap+0x23/0x30 [vfio] [<ffffffff81124ed8>] mmap_region+0x3d8/0x5e0 [<ffffffff811253e5>] do_mmap_pgoff+0x305/0x3c0 [<ffffffff8126f3f3>] ? call_rwsem_down_write_failed+0x13/0x20 [<ffffffff81111677>] vm_mmap_pgoff+0x67/0xa0 [<ffffffff811237e2>] SyS_mmap_pgoff+0x272/0x2e0 [<ffffffff810067e2>] SyS_mmap+0x22/0x30 [<ffffffff81648c59>] system_call_fastpath+0x16/0x1b ---[ end trace 6b0a8d2341444bdd ]--- ------------[ cut here ]------------ WARNING: at arch/x86/kernel/irq.c:182 do_IRQ+0x126/0x140() Thread not rescheduled for 95 jiffies CPU: 14 PID: 6684 Comm: foo Tainted: G W O 3.10.59+ 0000000000000009 ffff883f7fbc3ee0 ffffffff8163a12c ffff883f7fbc3f18 ffffffff8103f131 ffff887f48275ac0 000000000000002f 000000000000007c 0000000000000000 00007fadd1e00000 ffff883f7fbc3f78 ffffffff8103f19c Call Trace: <IRQ> [<ffffffff8163a12c>] dump_stack+0x19/0x1b [<ffffffff8103f131>] warn_slowpath_common+0x61/0x80 [<ffffffff8103f19c>] warn_slowpath_fmt+0x4c/0x50 [<ffffffff810bd917>] ? rcu_irq_exit+0x77/0xc0 [<ffffffff8164a556>] do_IRQ+0x126/0x140 [<ffffffff816407ef>] common_interrupt+0x6f/0x6f <EOI> [<ffffffff81640483>] ? _raw_spin_lock+0x13/0x30 [<ffffffff8111b621>] __pte_alloc+0x31/0xc0 [<ffffffff8111feac>] remap_pfn_range+0x45c/0x470 [<ffffffffa007f1f8>] vfio_pci_mmap+0x148/0x210 [vfio_pci] [<ffffffffa0025173>] vfio_device_fops_mmap+0x23/0x30 [vfio] [<ffffffff81124ed8>] mmap_region+0x3d8/0x5e0 [<ffffffff811253e5>] do_mmap_pgoff+0x305/0x3c0 [<ffffffff8126f3f3>] ? call_rwsem_down_write_failed+0x13/0x20 [<ffffffff81111677>] vm_mmap_pgoff+0x67/0xa0 [<ffffffff811237e2>] SyS_mmap_pgoff+0x272/0x2e0 [<ffffffff810067e2>] SyS_mmap+0x22/0x30 [<ffffffff81648c59>] system_call_fastpath+0x16/0x1b ---[ end trace 6b0a8d2341444bde ]--- ------------[ cut here ]------------ WARNING: at arch/x86/kernel/irq.c:182 do_IRQ+0x126/0x140() Thread not rescheduled for 45 jiffies CPU: 18 PID: 21726 Comm: foo Tainted: G O 3.10.59+ 0000000000000009 ffff88203f203ee0 ffffffff8163a13c ffff88203f203f18 ffffffff8103f131 ffff881ec5f1ad60 0000000000000016 000000000000006e 0000000000000000 ffffc939a6dd8000 ffff88203f203f78 ffffffff8103f19c Call Trace: <IRQ> [<ffffffff8163a13c>] dump_stack+0x19/0x1b [<ffffffff8103f131>] warn_slowpath_common+0x61/0x80 [<ffffffff8103f19c>] warn_slowpath_fmt+0x4c/0x50 [<ffffffff810bd917>] ? rcu_irq_exit+0x77/0xc0 [<ffffffff8164a556>] do_IRQ+0x126/0x140 [<ffffffff816407ef>] common_interrupt+0x6f/0x6f <EOI> [<ffffffff81640861>] ? retint_restore_args+0x13/0x13 [<ffffffff810346c7>] ? free_memtype+0x87/0x150 [<ffffffff8112bb46>] ? vunmap_page_range+0x1e6/0x2a0 [<ffffffff8112c5e1>] remove_vm_area+0x51/0x70 [<ffffffff810318a7>] iounmap+0x67/0xa0 [<ffffffff812757e5>] pci_iounmap+0x35/0x40 [<ffffffffa00973da>] vfio_pci_release+0x9a/0x150 [vfio_pci] [<ffffffffa0065cbc>] vfio_device_fops_release+0x1c/0x40 [vfio] [<ffffffff8114d82b>] __fput+0xdb/0x220 [<ffffffff8114d97e>] ____fput+0xe/0x10 [<ffffffff810614ac>] task_work_run+0xbc/0xe0 [<ffffffff81043d0e>] do_exit+0x3ce/0xe50 [<ffffffff8104557f>] do_group_exit+0x3f/0xa0 [<ffffffff81054769>] get_signal_to_deliver+0x1a9/0x5b0 [<ffffffff810023f8>] do_signal+0x48/0x5e0 [<ffffffff81056778>] ? k_getrusage+0x368/0x3d0 [<ffffffff810736e2>] ? default_wake_function+0x12/0x20 [<ffffffff816471c0>] ? kprobe_flush_task+0xc0/0x150 [<ffffffff81070684>] ? finish_task_switch+0xc4/0xe0 [<ffffffff810029f5>] do_notify_resume+0x65/0x80 [<ffffffff8164098e>] retint_signal+0x4d/0x9f ---[ end trace 3506c05e4a0af3e5 ]--- Signed-off-by: Joern Engel <joern@xxxxxxxxx> Signed-off-by: Spencer Baugh <sbaugh@xxxxxxxxxx> --- lib/ioremap.c | 1 + mm/memory.c | 1 + mm/vmalloc.c | 1 + 3 files changed, 3 insertions(+) diff --git a/lib/ioremap.c b/lib/ioremap.c index 86c8911..d38e46d 100644 --- a/lib/ioremap.c +++ b/lib/ioremap.c @@ -90,6 +90,7 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr, if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot)) return -ENOMEM; + cond_resched(); } while (pmd++, addr = next, addr != end); return 0; } diff --git a/mm/memory.c b/mm/memory.c index 388dcf9..1541880 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1656,6 +1656,7 @@ static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, if (remap_pte_range(mm, pmd, addr, next, pfn + (addr >> PAGE_SHIFT), prot)) return -ENOMEM; + cond_resched(); } while (pmd++, addr = next, addr != end); return 0; } diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 2faaa29..d503c8e 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -80,6 +80,7 @@ static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end) if (pmd_none_or_clear_bad(pmd)) continue; vunmap_pte_range(pmd, addr, next); + cond_resched(); } while (pmd++, addr = next, addr != end); } -- 2.5.0.rc3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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