Re: Crash in -next due to 'mm/vmalloc: replace opencoded 4-level page walkers'

From: Chris Wilson
Date: Fri Oct 28 2016 - 16:16:01 EST


On Fri, Oct 28, 2016 at 10:18:25AM -0700, Guenter Roeck wrote:
> Hi,
>
> when running sparc64 images in qemu, I see the following crash.
> This is with next-20161028.
>
> [ 2.530785] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff,max_idle_ns: 19112604462750000 ns
> [ 2.532359] kernel BUG at mm/memory.c:1881!
> [ 2.532798] \|/ ____ \|/
> [ 2.532798] "@'/ .. \`@"
> [ 2.532798] /_| \__/ |_\
> [ 2.532798] \__U_/
> [ 2.533250] swapper(1): Kernel bad sw trap 5 [#1]
> [ 2.533705] CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.0-rc2+ #1
> [ 2.534129] task: fffff8001f0af620 task.stack: fffff8001f0b0000
> [ 2.534505] TSTATE: 0000004480001605 TPC: 00000000005124d8 TNPC: 00000000005124dc Y: 00000035 Not tainted
> [ 2.535112] TPC: <apply_to_page_range+0x2f8/0x3a0>
> [ 2.535469] g0: 00000000009b1548 g1: 0000000000a4a990 g2: 0000000000a4a990 g3: 0000000000b37694
> [ 2.535857] g4: fffff8001f0af620 g5: 0000000000000000 g6: fffff8001f0b0000 g7: 0000000000000000
> [ 2.536236] o0: 000000000000001f o1: 00000000009ac2c0 o2: 0000000000000759 o3: 0000000000122000
> [ 2.536695] o4: 0000000000000000 o5: 00000000009ac2c0 sp: fffff8001f0b2d61 ret_pc: 00000000005124d0
> [ 2.537086] RPC: <apply_to_page_range+0x2f0/0x3a0>
> [ 2.537454] l0: 0000000000000000 l1: 0000000000002000 l2: fffff8001f10b000 l3: 0000000100002000
> [ 2.537843] l4: 0000000000aef910 l5: 0000000000a5e7e8 l6: 0000000100001fff l7: ffffffffff800000
> [ 2.538229] i0: 0000000000a5e7e8 i1: 0000000100000000 i2: 0000000100002000 i3: 000000000051e5e0
> [ 2.538613] i4: fffff8001f0b3708 i5: fffff8001f10c000 i6: fffff8001f0b2e51 i7: 000000000051e8e0
> [ 2.539007] I7: <vmap_page_range_noflush+0x40/0x80>
> [ 2.539387] Call Trace:
> [ 2.539765] [000000000051e8e0] vmap_page_range_noflush+0x40/0x80
> [ 2.540139] [000000000051e970] map_vm_area+0x50/0x80
> [ 2.540492] [000000000051f84c] __vmalloc_node_range+0x14c/0x260
> [ 2.540848] [000000000051f98c] __vmalloc_node+0x2c/0x40
> [ 2.541198] [00000000004d39cc] bpf_prog_alloc+0x2c/0xa0
> [ 2.541554] [00000000008129bc] bpf_prog_create+0x3c/0xa0
> [ 2.541916] [0000000000adb21c] ptp_classifier_init+0x20/0x4c
> [ 2.542271] [0000000000ad9808] sock_init+0x90/0xa0
> [ 2.542622] [0000000000426cb0] do_one_initcall+0x30/0x160
> [ 2.542978] [0000000000aaeaec] kernel_init_freeable+0x10c/0x1b0
> [ 2.543332] [00000000008e3324] kernel_init+0x4/0x100
> [ 2.543681] [0000000000405f04] ret_from_fork+0x1c/0x2c
>
> Bisect points to commit 0c79e3331f08 ("mm/vmalloc: replace opencoded 4-level
> page walkers"). Reverting this patch fixes the problem.

Hmm, apply_to_pte_range() has a BUG_ON(pmd_huge(*pmd)) but the old
vmap_pte_range() does not and neither has the code to handle that case.
Presuming that the BUG_ON() there is actually meaningful.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre