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authorDmitry Safonov <dima@arista.com>2018-03-31 01:33:11 +0100
committerJoerg Roedel <jroedel@suse.de>2018-05-03 14:38:58 +0200
commit6c50d79f66382d78918a768374839d6d1b606d3f (patch)
treee8f6bc7e6d0f0411e639268b5796867675e4adcf /drivers/iommu
parent6da6c0db5316275015e8cc2959f12a17584aeb64 (diff)
downloadlinux-6c50d79f66382d78918a768374839d6d1b606d3f.tar.bz2
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.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index accf58388bdb..6c4ea32ee6a9 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;