diff options
author | Dmitry Safonov <dima@arista.com> | 2018-03-31 01:33:11 +0100 |
---|---|---|
committer | Joerg Roedel <jroedel@suse.de> | 2018-05-03 14:38:58 +0200 |
commit | 6c50d79f66382d78918a768374839d6d1b606d3f (patch) | |
tree | e8f6bc7e6d0f0411e639268b5796867675e4adcf /drivers/iommu | |
parent | 6da6c0db5316275015e8cc2959f12a17584aeb64 (diff) | |
download | op-kernel-dev-6c50d79f66382d78918a768374839d6d1b606d3f.zip op-kernel-dev-6c50d79f66382d78918a768374839d6d1b606d3f.tar.gz |
iommu/vt-d: Ratelimit each dmar fault printing
There is a ratelimit for printing, but it's incremented each time the
cpu recives dmar fault interrupt. While one interrupt may signal about
*many* faults.
So, measuring the impact it turns out that reading/clearing one fault
takes < 1 usec, and printing info about the fault takes ~170 msec.
Having in mind that maximum number of fault recording registers per
remapping hardware unit is 256.. IRQ handler may run for (170*256) msec.
And as fault-serving loop runs without a time limit, during servicing
new faults may occur..
Ratelimit each fault printing rather than each irq printing.
Fixes: commit c43fce4eebae ("iommu/vt-d: Ratelimit fault handler")
BUG: spinlock lockup suspected on CPU#0, CliShell/9903
lock: 0xffffffff81a47440, .magic: dead4ead, .owner: kworker/u16:2/8915, .owner_cpu: 6
CPU: 0 PID: 9903 Comm: CliShell
Call Trace:$\n'
[..] dump_stack+0x65/0x83$\n'
[..] spin_dump+0x8f/0x94$\n'
[..] do_raw_spin_lock+0x123/0x170$\n'
[..] _raw_spin_lock_irqsave+0x32/0x3a$\n'
[..] uart_chars_in_buffer+0x20/0x4d$\n'
[..] tty_chars_in_buffer+0x18/0x1d$\n'
[..] n_tty_poll+0x1cb/0x1f2$\n'
[..] tty_poll+0x5e/0x76$\n'
[..] do_select+0x363/0x629$\n'
[..] compat_core_sys_select+0x19e/0x239$\n'
[..] compat_SyS_select+0x98/0xc0$\n'
[..] sysenter_dispatch+0x7/0x25$\n'
[..]
NMI backtrace for cpu 6
CPU: 6 PID: 8915 Comm: kworker/u16:2
Workqueue: dmar_fault dmar_fault_work
Call Trace:$\n'
[..] wait_for_xmitr+0x26/0x8f$\n'
[..] serial8250_console_putchar+0x1c/0x2c$\n'
[..] uart_console_write+0x40/0x4b$\n'
[..] serial8250_console_write+0xe6/0x13f$\n'
[..] call_console_drivers.constprop.13+0xce/0x103$\n'
[..] console_unlock+0x1f8/0x39b$\n'
[..] vprintk_emit+0x39e/0x3e6$\n'
[..] printk+0x4d/0x4f$\n'
[..] dmar_fault+0x1a8/0x1fc$\n'
[..] dmar_fault_work+0x15/0x17$\n'
[..] process_one_work+0x1e8/0x3a9$\n'
[..] worker_thread+0x25d/0x345$\n'
[..] kthread+0xea/0xf2$\n'
[..] ret_from_fork+0x58/0x90$\n'
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r-- | drivers/iommu/dmar.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index accf5838..6c4ea32 100644 --- a/drivers/iommu/dmar.c +++ b/drivers/iommu/dmar.c @@ -1618,17 +1618,13 @@ irqreturn_t dmar_fault(int irq, void *dev_id) int reg, fault_index; u32 fault_status; unsigned long flag; - bool ratelimited; static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); - /* Disable printing, simply clear the fault when ratelimited */ - ratelimited = !__ratelimit(&rs); - raw_spin_lock_irqsave(&iommu->register_lock, flag); fault_status = readl(iommu->reg + DMAR_FSTS_REG); - if (fault_status && !ratelimited) + if (fault_status && __ratelimit(&rs)) pr_err("DRHD: handling fault status reg %x\n", fault_status); /* TBD: ignore advanced fault log currently */ @@ -1638,6 +1634,8 @@ irqreturn_t dmar_fault(int irq, void *dev_id) fault_index = dma_fsts_fault_record_index(fault_status); reg = cap_fault_reg_offset(iommu->cap); while (1) { + /* Disable printing, simply clear the fault when ratelimited */ + bool ratelimited = !__ratelimit(&rs); u8 fault_reason; u16 source_id; u64 guest_addr; |