Re: [PATCH V2 2/2] mm/pgtable/debug: Add test validating architecture page table helpers

[Christophe Leroy]

Le 12/09/2019 Ã 17:52, Christophe Leroy a ÃcritÂ:
> Le 12/09/2019 Ã 17:36, Christophe Leroy a ÃcritÂ:
> > Le 12/09/2019 Ã 17:00, Christophe Leroy a ÃcritÂ:
> > > On 09/12/2019 06:02 AM, Anshuman Khandual wrote:
> > > > This adds a test module which will validate architecture page table 
> > > > helpers
> > > > and accessors regarding compliance with generic MM semantics 
> > > > expectations.
> > > > This will help various architectures in validating changes to the 
> > > > existing
> > > > page table helpers or addition of new ones.
> > > >
> > > > Test page table and memory pages creating it's entries at various 
> > > > level are
> > > > all allocated from system memory with required alignments. If memory 
> > > > pages
> > > > with required size and alignment could not be allocated, then all 
> > > > depending
> > > > individual tests are skipped.
> > >
> > > Build failure on powerpc book3s/32. This is because asm/highmem.h is 
> > > missing. It can't be included from asm/book3s/32/pgtable.h because it 
> > > creates circular dependency. So it has to be included from 
> > > mm/arch_pgtable_test.c
> >
> > In fact it is <linux/highmem.h> that needs to be added, adding 
> > <asm/highmem.h> directly provokes build failure at link time.
>
> I get the following failure,
>
> [ÂÂÂ 0.704685] ------------[ cut here ]------------
> [ÂÂÂ 0.709239] initcall arch_pgtable_tests_init+0x0/0x228 returned with 
> preemption imbalance

preempt_disable() is called from kmap_atomic() which is called from 
pte_alloc_map() via pte_offset_map().

pte_unmap() has to be called to release the mapped pte and re-enable 
preemtion.

Christophe


> [ÂÂÂ 0.717539] WARNING: CPU: 0 PID: 1 at init/main.c:952 
> do_one_initcall+0x18c/0x1d4
> [ÂÂÂ 0.724922] CPU: 0 PID: 1 Comm: swapper Not tainted 
> 5.3.0-rc7-s3k-dev-00880-g28fd02a838e5-dirty #2307
> [ÂÂÂ 0.734070] NIP:Â c070e674 LR: c070e674 CTR: c001292c
> [ÂÂÂ 0.739084] REGS: df4a5dd0 TRAP: 0700ÂÂ Not tainted 
> (5.3.0-rc7-s3k-dev-00880-g28fd02a838e5-dirty)
> [ÂÂÂ 0.747975] MSR:Â 00029032 <EE,ME,IR,DR,RI>Â CR: 28000222Â XER: 00000000
> [ÂÂÂ 0.754628]
> [ÂÂÂ 0.754628] GPR00: c070e674 df4a5e88 df4a0000 0000004e 0000000a 
> 00000000 000000ca 38207265
> [ÂÂÂ 0.754628] GPR08: 00001032 00000800 00000000 00000000 22000422 
> 00000000 c0004a7c 00000000
> [ÂÂÂ 0.754628] GPR16: 00000000 00000000 00000000 00000000 00000000 
> c0810000 c0800000 c0816f30
> [ÂÂÂ 0.754628] GPR24: c070dc20 c074702c 00000006 0000009c 00000000 
> c0724494 c074e140 00000000
> [ÂÂÂ 0.789339] NIP [c070e674] do_one_initcall+0x18c/0x1d4
> [ÂÂÂ 0.794435] LR [c070e674] do_one_initcall+0x18c/0x1d4
> [ÂÂÂ 0.799437] Call Trace:
> [ÂÂÂ 0.801867] [df4a5e88] [c070e674] do_one_initcall+0x18c/0x1d4 
> (unreliable)
> [ÂÂÂ 0.808694] [df4a5ee8] [c070e8c0] kernel_init_freeable+0x204/0x2dc
> [ÂÂÂ 0.814830] [df4a5f28] [c0004a94] kernel_init+0x18/0x110
> [ÂÂÂ 0.820107] [df4a5f38] [c00122ac] ret_from_kernel_thread+0x14/0x1c
> [ÂÂÂ 0.826220] Instruction dump:
> [ÂÂÂ 0.829161] 4beb1069 7d2000a6 61298000 7d200124 89210008 2f890000 
> 41be0048 3c60c06a
> [ÂÂÂ 0.836849] 38a10008 7fa4eb78 3863cacc 4b915115 <0fe00000> 4800002c 
> 81220070 712a0004
> [ÂÂÂ 0.844723] ---[ end trace 969d686308d40b33 ]---
>
> Then starting init fails:
>
> [ÂÂÂ 3.894074] Run /init as init process
> [ÂÂÂ 3.898403] Failed to execute /init (error -14)
> [ÂÂÂ 3.903009] Run /sbin/init as init process
> [ÂÂÂ 3.907172] Run /etc/init as init process
> [ÂÂÂ 3.911251] Run /bin/init as init process
> [ÂÂÂ 3.915513] Run /bin/sh as init process
> [ÂÂÂ 3.919471] Starting init: /bin/sh exists but couldn't execute it 
> (error -14)
> [ 3.926732] Kernel panic - not syncing: No working init found. Try 
> passing init= option to kernel. See Linux 
> Documentation/admin-guide/init.rst for guidance.
> [ÂÂÂ 3.940864] CPU: 0 PID: 1 Comm: init Tainted: GÂÂÂÂÂÂÂ W 
> 5.3.0-rc7-s3k-dev-00880-g28fd02a838e5-dirty #2307
> [ÂÂÂ 3.951165] Call Trace:
> [ÂÂÂ 3.953617] [df4a5ec8] [c002392c] panic+0x12c/0x320 (unreliable)
> [ÂÂÂ 3.959621] [df4a5f28] [c0004b8c] rootfs_mount+0x0/0x2c
> [ÂÂÂ 3.964849] [df4a5f38] [c00122ac] ret_from_kernel_thread+0x14/0x1c
>
>
> Christophe