Re: 2.6.24-mm1

From: Ingo Molnar
Date: Wed Feb 06 2008 - 06:15:57 EST


* KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:

> Hi Ingo,
>
> > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24/2.6.24-mm1/
> >
> >
> > - The x86 git tree has been dropped due to runtime failure on one of my test
> > machines
>
> My PC display warning message at boot time.
> Could I help your debugging?
>
> ----------------------------------------------------------------------------------------------
>
> end_request: I/O error, dev fd0, sector 0
> Welcome to CentOS release 5 (Final)
> Press 'I' to enter interactive startup.
> ------------[ cut here ]------------
> WARNING: at kernel/lockdep.c:2037 _spin_unlock_irq+0x20/0x23()
> Modules linked in: usb_storage ahci ata_piix libata ehci_hcd ohci_hcd uhci_hcd
> Pid: 1085, comm: hwclock Not tainted 2.6.24-mm1 #1
> [<c011e75f>] warn_on_slowpath+0x40/0x4f
> [<c012cc1b>] __kernel_text_address+0x18/0x23
> [<c0105710>] dump_trace+0xb3/0xbd
> [<c0137bd1>] check_usage_forwards+0x16/0x35
> [<c0137d5d>] mark_lock+0x16d/0x389
> [<c03ed8f2>] _spin_unlock_irq+0x20/0x23
> [<c0114675>] hpet_rtc_interrupt+0xe6/0x2a7
> [<c014582b>] handle_IRQ_event+0x13/0x3d
> [<c01466d6>] handle_edge_irq+0xc2/0xff
> [<c010664a>] do_IRQ+0x6e/0x84
> [<c010516e>] common_interrupt+0x2e/0x34
> [<c03e007b>] nv_probe+0x1281/0x13bc
> [<c03ef010>] do_page_fault+0x15f/0x4ae
> [<c03eeeb1>] do_page_fault+0x0/0x4ae
> [<c03edb62>] error_code+0x72/0x78
> =======================
> ---[ end trace 908d580e4399e39b ]---

should be fixed by the commit below. (already upstream)

Ingo

-------------->
commit 795d45b22c079946332bf3825afefe5a981a97b6
Author: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Date: Mon Feb 4 16:48:10 2008 +0100

x86: fix RTC lockdep warning: potential hardirq recursion

After disabling both CONFIG_DEBUG_LOCKING_API_SELFTESTS and netconsole
(using current mainline) I get a login prompt, and also...

[ 5.181668] SELinux: policy loaded with handle_unknown=deny
[ 5.183315] type=1403 audit(1202100038.157:3): policy loaded auid=4294967295 ses=4294967295
[ 5.822073] SELinux: initialized (dev usbfs, type usbfs), uses genfs_contexts
[ 7.819146] ------------[ cut here ]------------
[ 7.819146] WARNING: at kernel/lockdep.c:2033 trace_hardirqs_on+0x9b/0x10d()
[ 7.819146] Modules linked in: generic ext3 jbd ide_disk ide_core
[ 7.819146] Pid: 399, comm: hwclock Not tainted 2.6.24 #4
[ 7.819146] [<c011d140>] warn_on_slowpath+0x41/0x51
[ 7.819146] [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[ 7.819146] [<c013770c>] ? check_usage_forwards+0x19/0x3b
[ 7.819146] [<c01390c4>] ? __lock_acquire+0xac3/0xb0b
[ 7.819146] [<c0108c98>] ? native_sched_clock+0x8b/0x9f
[ 7.819146] [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[ 7.819146] [<c030ca6c>] ? _spin_unlock_irq+0x22/0x42
[ 7.819146] [<c013848b>] trace_hardirqs_on+0x9b/0x10d
[ 7.819146] [<c030ca6c>] _spin_unlock_irq+0x22/0x42
[ 7.819146] [<c011481e>] hpet_rtc_interrupt+0xdf/0x290
[ 7.819146] [<c014ea90>] handle_IRQ_event+0x1a/0x46
[ 7.819146] [<c014f8ea>] handle_edge_irq+0xbe/0xff
[ 7.819146] [<c0106e08>] do_IRQ+0x6d/0x84
[ 7.819146] [<c0105596>] common_interrupt+0x2e/0x34
[ 7.819146] [<c013007b>] ? ktime_get_ts+0x8/0x3f
[ 7.819146] [<c0139420>] ? lock_release+0x167/0x16f
[ 7.819146] [<c017974a>] ? core_sys_select+0x2c/0x327
[ 7.819146] [<c0179792>] core_sys_select+0x74/0x327
[ 7.819146] [<c0108c98>] ? native_sched_clock+0x8b/0x9f
[ 7.819146] [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[ 7.819146] [<c030ca6c>] ? _spin_unlock_irq+0x22/0x42
[ 7.819146] [<c01384d6>] ? trace_hardirqs_on+0xe6/0x10d
[ 7.819146] [<c030ca77>] ? _spin_unlock_irq+0x2d/0x42
[ 7.819146] [<c023b437>] ? rtc_do_ioctl+0x11b/0x677
[ 7.819146] [<c01c487e>] ? inode_has_perm+0x5e/0x68
[ 7.819146] [<c01364a9>] ? lock_release_holdtime+0x50/0x56
[ 7.819146] [<c0108c98>] ? native_sched_clock+0x8b/0x9f
[ 7.819146] [<c01c490b>] ? file_has_perm+0x83/0x8c
[ 7.819146] [<c023ba08>] ? rtc_ioctl+0xf/0x11
[ 7.819146] [<c017898d>] ? do_ioctl+0x55/0x67
[ 7.819146] [<c0179d15>] sys_select+0x93/0x163
[ 7.819146] [<c0104b39>] ? sysenter_past_esp+0x9a/0xa5
[ 7.819146] [<c0104afe>] sysenter_past_esp+0x5f/0xa5
[ 7.819146] =======================
[ 7.819146] ---[ end trace 96540ca301ffb84c ]---
[ 7.819210] rtc: lost 6 interrupts
[ 7.870668] type=1400 audit(1202128840.794:4): avc: denied { audit_write } for pid=399 comm="hwclock" capability=29 scontext=system_u:system_r:hwclock_t:s0 tcontext=system_u:system_r:hwclock_t:s0 tclass=capability
[ 9.538866] input: PC Speaker as /class/input/input5

Because hpet_rtc_interrupt()'s call to get_rtc_time() ends up
resolving to include/asm-generic/rtc.h's (hilariously inlined)
get_rtc_time(), which does spin_unlock_irq() from hard IRQ context.

The obvious patch fixes it.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

diff --git a/include/asm-generic/rtc.h b/include/asm-generic/rtc.h
index d3238f1..dd1bed8 100644
--- a/include/asm-generic/rtc.h
+++ b/include/asm-generic/rtc.h
@@ -35,10 +35,11 @@
static inline unsigned char rtc_is_updating(void)
{
unsigned char uip;
+ unsigned long flags;

- spin_lock_irq(&rtc_lock);
+ spin_lock_irqsave(&rtc_lock, flags);
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
- spin_unlock_irq(&rtc_lock);
+ spin_unlock_irqrestore(&rtc_lock, flags);
return uip;
}

@@ -46,6 +47,8 @@ static inline unsigned int get_rtc_time(struct rtc_time *time)
{
unsigned long uip_watchdog = jiffies;
unsigned char ctrl;
+ unsigned long flags;
+
#ifdef CONFIG_MACH_DECSTATION
unsigned int real_year;
#endif
@@ -72,7 +75,7 @@ static inline unsigned int get_rtc_time(struct rtc_time *time)
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value.
*/
- spin_lock_irq(&rtc_lock);
+ spin_lock_irqsave(&rtc_lock, flags);
time->tm_sec = CMOS_READ(RTC_SECONDS);
time->tm_min = CMOS_READ(RTC_MINUTES);
time->tm_hour = CMOS_READ(RTC_HOURS);
@@ -83,7 +86,7 @@ static inline unsigned int get_rtc_time(struct rtc_time *time)
real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
ctrl = CMOS_READ(RTC_CONTROL);
- spin_unlock_irq(&rtc_lock);
+ spin_unlock_irqrestore(&rtc_lock, flags);

if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
--
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