Skip to content

K
kernel_linux

OpenHarmony / kernel_linux
上一次同步 大约 4 年

通知 14
Star 8
Fork 2
K
kernel_linux
切换分支/标签
  1. 17 4月, 2008 4 次提交
  3. 30 1月, 2008 4 次提交
  5. 25 1月, 2008 1 次提交
  7. 22 1月, 2008 1 次提交
  9. 19 12月, 2007 1 次提交
    • I
      x86: fix "Kernel panic - not syncing: IO-APIC + timer doesn't work!" · 4aae0702
      由 Ingo Molnar 提交于 
      this is the tale of a full day spent debugging an ancient but elusive bug.

after booting up thousands of random .config kernels, i finally happened
to generate a .config that produced the following rare bootup failure
on 32-bit x86:

| ..TIMER: vector=0x31 apic1=0 pin1=2 apic2=-1 pin2=-1
| ..MP-BIOS bug: 8254 timer not connected to IO-APIC
| ...trying to set up timer (IRQ0) through the 8259A ...  failed.
| ...trying to set up timer as Virtual Wire IRQ... failed.
| ...trying to set up timer as ExtINT IRQ... failed :(.
| Kernel panic - not syncing: IO-APIC + timer doesn't work!  Boot with apic=debug
| and send a report.  Then try booting with the 'noapic' option

this bug has been reported many times during the years, but it was never
reproduced nor fixed.

the bug that i hit was extremely sensitive to .config details.

First i did a .config-bisection - suspecting some .config detail.
That led to CONFIG_X86_MCE: enabling X86_MCE magically made the bug disappear
and the system would boot up just fine.

Debugging my way through the MCE code ended up identifying two unlikely
candidates: the thing that made a real difference to the hang was that
X86_MCE did two printks:

 Intel machine check architecture supported.
 Intel machine check reporting enabled on CPU#1.

Adding the same printks to a !CONFIG_X86_MCE kernel made the bug go away!

this left timing as the main suspect: i experimented with adding various
udelay()s to the arch/x86/kernel/io_apic_32.c:check_timer() function, and
the race window turned out to be narrower than 30 microseconds (!).

That made debugging especially funny, debugging without having printk
ability before the bug hits is ... interesting ;-)

eventually i started suspecting IRQ activities - those are pretty much the
only thing that happen this early during bootup and have the timescale of
a few dozen microseconds. Also, check_timer() changes the IRQ hardware
in various creative ways, so the main candidate became IRQ0 interaction.

i've added a counter to track timer irqs (on which core they arrived, at
what exact time, etc.) and found that no timer IRQ would arrive after the
bug condition hits - even if we re-enable IRQ0 and re-initialize the i8259A,
but that we'd get a small number of timer irqs right around the time when we
call the check_timer() function.

Eventually i got the following backtrace triggered from debug code in the
timer interrupt:

...trying to set up timer as Virtual Wire IRQ... failed.
...trying to set up timer as ExtINT IRQ...
Pid: 1, comm: swapper Not tainted (2.6.24-rc5 #57)
EIP: 0060:[<c044d57e>] EFLAGS: 00000246 CPU: 0
EIP is at _spin_unlock_irqrestore+0x5/0x1c
EAX: c0634178 EBX: 00000000 ECX: c4947d63 EDX: 00000246
ESI: 00000002 EDI: 00010031 EBP: c04e0f2e ESP: f7c41df4
 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
 CR0: 8005003b CR2: ffe04000 CR3: 00630000 CR4: 000006d0
 DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
 DR6: ffff0ff0 DR7: 00000400
  [<c05f5784>] setup_IO_APIC+0x9c3/0xc5c

the spin_unlock() was called from init_8259A(). Wait ... we have an IRQ0
entry while we are in the middle of setting up the local APIC, the i8259A
and the PIT??

That is certainly not how it's supposed to work! check_timer() was supposed
to be called with irqs turned off - but this eroded away sometime in the
past. This code would still work most of the time because this code runs
very quickly, but just the right timing conditions are present and IRQ0
hits in this small, ~30 usecs window, timer irqs stop and the system does
not boot up. Also, given how early this is during bootup, the hang is
very deterministic - but it would only occur on certain machines (and
certain configs).

The fix was quite simple: disable/restore interrupts properly in this
function. With that in place the test-system now boots up just fine.

(64-bit x86 io_apic_64.c had the same bug.)

Phew! One down, only 1500 other kernel bugs are left ;-)
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      4aae0702
  11. 27 11月, 2007 1 次提交
  13. 20 11月, 2007 1 次提交
  15. 20 10月, 2007 2 次提交
  17. 18 10月, 2007 1 次提交
  19. 17 10月, 2007 1 次提交
  21. 11 10月, 2007 2 次提交
  23. 21 8月, 2007 1 次提交
    • L
      ACPI: boot correctly with "nosmp" or "maxcpus=0" · 61ec7567
      由 Len Brown 提交于 
      In MPS mode, "nosmp" and "maxcpus=0" boot a UP kernel with IOAPIC disabled.
However, in ACPI mode, these parameters didn't completely disable
the IO APIC initialization code and boot failed.

init/main.c:
	Disable the IO_APIC if "nosmp" or "maxcpus=0"
	undefine disable_ioapic_setup() when it doesn't apply.

i386:
	delete ioapic_setup(), it was a duplicate of parse_noapic()
	delete undefinition of disable_ioapic_setup()

x86_64:
	rename disable_ioapic_setup() to parse_noapic() to match i386
	define disable_ioapic_setup() in header to match i386

http://bugzilla.kernel.org/show_bug.cgi?id=1641Acked-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLen Brown <len.brown@intel.com>
      61ec7567
  25. 13 8月, 2007 1 次提交
  27. 22 7月, 2007 2 次提交
  29. 18 7月, 2007 1 次提交
    • R
      Freezer: make kernel threads nonfreezable by default · 83144186
      由 Rafael J. Wysocki 提交于 
      Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NNigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      83144186
  31. 09 5月, 2007 1 次提交
  33. 03 5月, 2007 3 次提交
  35. 09 4月, 2007 1 次提交
  37. 01 3月, 2007 1 次提交
    • E
      [PATCH] x86_64/i386 irq: Fix !CONFIG_SMP compilation · 2ff7354f
      由 Eric W. Biederman 提交于 
      When removing set_native_irq I missed the fact that it was
called in a couple of places that were compiled even when
SMP support is disabled.  And since the irq_desc[].affinity
field only exists in SMP things broke.

Thanks to Simon Arlott <simon@arlott.org> for spotting this.

There are a couple of ways to fix this but the simplest one
is to just remove the assignments.  The affinity field is only
used to display a value to the user, and nothing on either i386
or x86_64 reads it or depends on it being any particlua value,
so skipping the assignment is safe.  The assignment that
is being removed is just for the initial affinity value before
the user explicitly sets it.  The irq_desc array initializes
this field to CPU_MASK_ALL so the field is initialized to
a reasonable value in the SMP case without being set.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2ff7354f
  39. 27 2月, 2007 1 次提交
  41. 17 2月, 2007 3 次提交
  43. 13 2月, 2007 2 次提交
  45. 10 2月, 2007 1 次提交
  47. 08 2月, 2007 1 次提交
  49. 31 1月, 2007 1 次提交
    • E
      [PATCH] i386: In assign_irq_vector look at all vectors before giving up · 8339f000
      由 Eric W. Biederman 提交于 
      When the world was a simple and static place setting up irqs was easy.
It sufficed to allocate a linux irq number and a find a free cpu
vector we could receive that linux irq on.  In those days it was
a safe assumption that any allocated vector was actually in use
so after one global pass through all of the vectors we would have
none left.

These days things are much more dynamic with interrupt controllers
(in the form of MSI or MSI-X) appearing on plug in cards and linux
irqs appearing and disappearing.  As these irqs come and go vectors
are allocated and freed,  invalidating the ancient assumption that all
allocated vectors stayed in use forever.

So this patch modifies the vector allocator to walk through every
possible vector before giving up, and to check to see if a vector
is in use before assigning it.  With these changes we stop leaking
freed vectors and it becomes possible to allocate and free irq vectors
all day long.

This changed was modeled after the vector allocator on x86_64 where
this limitation has already been removed.  In essence we don't update
the static variables that hold the position of the last vector we
allocated until have successfully allocated another vector.  This
allows us to detect if we have completed one complete scan through
all of the possible vectors.
Acked-by: NAuke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8339f000
  51. 10 12月, 2006 1 次提交
    • A
      [PATCH] i386: Fix io_apic.c warning · 306a22c2
      由 Andi Kleen 提交于 
      gcc 4.2 warns

linux/arch/i386/kernel/io_apic.c: In function ‘create_irq’:
linux/arch/i386/kernel/io_apic.c:2488: warning: ‘vector’ may be used uninitialized in this function

The warning is false, but somewhat legitimate so work around it.
Signed-off-by: NAndi Kleen <ak@suse.de>
      306a22c2