* Borislav Petkov <b...@alien8.de> wrote:
> On Fri, Jun 26, 2015 at 05:33:22PM +0800, Zhu Guihua wrote:
> > The following lockdep warning occurrs when running with latest kernel:
> > [ 3.178000] ------------[ cut here ]------------
> > [ 3.183000] WARNING: CPU: 128 PID: 0 at kernel/locking/lockdep.c:2755
> > lockdep_trace_alloc+0xdd/0xe0()
> > [ 3.193000] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))
> > [ 3.199000] Modules linked in:
> >
> > [ 3.203000] CPU: 128 PID: 0 Comm: swapper/128 Not tainted 4.1.0-rc3 #70
> > [ 3.221000] 0000000000000000 2d6601fb3e6d4e4c ffff88086fd5fc38
> > ffffffff81773f0a
> > [ 3.230000] 0000000000000000 ffff88086fd5fc90 ffff88086fd5fc78
> > ffffffff8108c85a
> > [ 3.238000] ffff88086fd60000 0000000000000092 ffff88086fd60000
> > 00000000000000d0
> > [ 3.246000] Call Trace:
> > [ 3.249000] [<ffffffff81773f0a>] dump_stack+0x4c/0x65
> > [ 3.255000] [<ffffffff8108c85a>] warn_slowpath_common+0x8a/0xc0
> > [ 3.261000] [<ffffffff8108c8e5>] warn_slowpath_fmt+0x55/0x70
> > [ 3.268000] [<ffffffff810ee24d>] lockdep_trace_alloc+0xdd/0xe0
> > [ 3.274000] [<ffffffff811cda0d>] __alloc_pages_nodemask+0xad/0xca0
> > [ 3.281000] [<ffffffff810ec7ad>] ? __lock_acquire+0xf6d/0x1560
> > [ 3.288000] [<ffffffff81219c8a>] alloc_page_interleave+0x3a/0x90
> > [ 3.295000] [<ffffffff8121b32d>] alloc_pages_current+0x17d/0x1a0
> > [ 3.301000] [<ffffffff811c869e>] ? __get_free_pages+0xe/0x50
> > [ 3.308000] [<ffffffff811c869e>] __get_free_pages+0xe/0x50
> > [ 3.314000] [<ffffffff8102640b>] init_espfix_ap+0x17b/0x320
> > [ 3.320000] [<ffffffff8105c691>] start_secondary+0xf1/0x1f0
> > [ 3.327000] ---[ end trace 1b3327d9d6a1d62c ]---
> >
> > As we alloc pages with GFP_KERNEL in init_espfix_ap() which is called
> > before enabled local irq, and the lockdep sub-system considers this
> > behaviour as allocating memory with GFP_FS with local irq disabled,
> > then trigger the warning as mentioned about.
> >
> > So we allocate them on the boot CPU side when the target CPU is bringing
> > up by the primary CPU, and hand them over to the secondary CPU.
> >
> > Signed-off-by: Zhu Guihua <zhugh.f...@cn.fujitsu.com>
> > ---
> > v2:
> > -allocate espfix stack pages when the targert CPU is bringing up by the
> > primary CPU
> > -commit messages changed
> > v1:
> > -Alloc the page on the node the target CPU is on.
> > RFC v2:
> > -Let the boot up routine init the espfix stack for the target cpu after it
> > booted.
>
> Looks ok to me and it works on the 16-node NUMA guest I was triggering the
> splat
> with.
>
> hpa, is that what you had in mind?
Looks good to me, but please split it into two parts: one that pushes down the
CPU
index - another that does the actual change.
Should this break anything then being in two parts will make it much easier to
bisect to.
Thanks,
Ingo
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