* Alexey Zaytsev <alexey.zaytsev@xxxxxxxxx> wrote: > On Thu, Dec 11, 2008 at 15:40, Alexey Zaytsev <alexey.zaytsev@xxxxxxxxx> wrote: > > On Thu, Dec 11, 2008 at 12:04, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote: > >> Hi all, > >> > >> Changes since 20081210: > >> > >> New tree: > >> nommu > >> > >> Undropped tree: > >> sound > >> > >> Dropped trees (temporarily): > >> v4l-dvb (build problem) > >> mtd (difficult conflicts) > >> drm (build problem) > >> semaphore-removal (due to unfixed conflicts against Linus' tree) > >> cpu_alloc (build problem) > >> perfmon3 (concerns from the x86 team) > >> audit (difficult conflicts) > >> nommu (build problem) > >> staging (build failure) > >> > >> The driver-core tree gained a build failure that needed a commit reverted. > >> > >> The ftrace tree gained a conflict against Linus' tree. > >> > >> The pci tree gained a conflict against the driver-core tree. > >> > >> The mtd tree gained 3 conflicts against the arm tree which I could not > >> easily resolve, so it was dropped. > >> > >> The ttydev tree gained a conflict against the async_tx tree requiring a > >> commit from the async_tx tree to be reverted. > >> > >> The nommu tree gained conflicts against the slab and kmemcheck trees and > >> also a build failure so it was dropped. > >> > >> ---------------------------------------------------------------------------- > > > > Hi. > > > > I'm seeing this warning early in boot logs. It does not appear on 2.6.28-rc7. > > Not sure how long it's been around. Haven't built -next for some time. > > > > [ 0.004000] Intel machine check reporting enabled on CPU#0. > > [ 0.004000] using mwait in idle threads. > > [ 0.004000] Checking 'hlt' instruction... <4>------------[ cut here > > ]------------ > > [ 0.004167] WARNING: at kernel/sched.c:4364 sub_preempt_count+0xae/0xc0() > > [ 0.004266] Hardware name: HP Compaq nx7300 (GB848ES#ACB) > > [ 0.004361] Modules linked in: > > [ 0.004497] Pid: 0, comm: swapper Not tainted 2.6.28-rc8-next-20081211 #117 > > [ 0.004595] Call Trace: > > [ 0.004689] [<c01324d6>] warn_slowpath+0x86/0xa0 > > [ 0.004789] [<c0155d00>] ? check_usage_forwards+0x10/0xb0 > > [ 0.004886] [<c015394a>] ? save_trace+0x3a/0xa0 > > [ 0.004981] [<c015742d>] ? mark_lock+0x37d/0xe00 > > [ 0.005076] [<c01580f9>] ? __lock_acquire+0x249/0x610 > > [ 0.005175] [<c04a3a02>] ? _spin_unlock_irq+0x22/0x50 > > [ 0.005272] [<c0158e50>] ? trace_hardirqs_on_caller+0x70/0x1a0 > > [ 0.005369] [<c04a3a0d>] ? _spin_unlock_irq+0x2d/0x50 > > [ 0.005465] [<c0124bfe>] sub_preempt_count+0xae/0xc0 > > [ 0.005564] [<c0137012>] _local_bh_enable+0x52/0xc0 > > [ 0.005661] [<c013725f>] __do_softirq+0x11f/0x170 > > [ 0.005756] [<c0137140>] ? __do_softirq+0x0/0x170 > > [ 0.005851] <IRQ> [<c0137729>] ? irq_exit+0x89/0xa0 > > [ 0.005993] [<c01059ed>] ? do_IRQ+0xad/0x120 > > [ 0.006088] [<c0103aac>] ? common_interrupt+0x2c/0x34 > > [ 0.006184] [<c013007b>] ? mmput+0x2b/0xc0 > > [ 0.006281] [<c06735a8>] ? check_bugs+0xb8/0xe0 > > [ 0.006379] [<c066b7ea>] ? start_kernel+0x26a/0x310 > > [ 0.006475] [<c066b270>] ? unknown_bootoption+0x0/0x210 > > [ 0.006572] [<c066b077>] ? __init_begin+0x77/0xb0 > > [ 0.006674] ---[ end trace 4eaa2a86a8e2da22 ]--- > > [ 0.016004] OK. > > [ 0.016560] ACPI: Core revision 20081031 > > [ 0.044495] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1 > > > > Config and full dmesg attached. > > > > The warning can also be reproduced in qemu, so it was easy to bisect. > > commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd > Author: Nick Piggin <nickpiggin@xxxxxxxxxxxx> > Date: Tue Sep 30 20:50:27 2008 +1000 > > sched: improve preempt debugging > > This patch helped me out with a problem I recently had.... > > Basically, when the kernel lock is held, then preempt_count > underflow does not > get detected until it is released which may be a long time (and arbitrarily, > eg at different points it may be rescheduled). If the bkl is released at > schedule, the resulting output is actually fairly cryptic... > > With any other lock that elevates preempt_count, it is illegal to schedule > under it (which would get found pretty quickly). bkl allows scheduling with > preempt_count elevated, which makes underflows hard to debug. > > Signed-off-by: Ingo Molnar <mingo@xxxxxxx> > > I understand that not this particular commit is buggy, but at least > I've got someone to add to the CC. ;) > > Also the author's e-mail looks suspicious. Suspicious in what way? Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
