Subject: Re: [PATCH V3 10/15] arch/kmap: Define kmap_atomic_prot() for all arch's

From: Guenter Roeck <[email-masked]>
Date: Sun, 17 May 2020 10:37:22 -0700

Hi,

On Thu, May 07, 2020 at 07:59:58AM -0700, [email-masked] wrote:
> From: Ira Weiny <[email-masked]>
> 
> To support kmap_atomic_prot(), all architectures need to support
> protections passed to their kmap_atomic_high() function.  Pass
> protections into kmap_atomic_high() and change the name to
> kmap_atomic_high_prot() to match.
> 
> Then define kmap_atomic_prot() as a core function which calls
> kmap_atomic_high_prot() when needed.
> 
> Finally, redefine kmap_atomic() as a wrapper of kmap_atomic_prot() with
> the default kmap_prot exported by the architectures.
> 
> Reviewed-by: Christoph Hellwig <[email-masked]>
> Signed-off-by: Ira Weiny <[email-masked]>

This patch causes a variety of crashes whem booting powerpc images in qemu.

There are lots of warnings such as:

WARNING: CPU: 0 PID: 0 at lib/locking-selftest.c:743 irqsafe1_hard_spin_12+0x50/0xb0
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Tainted: G        W         5.7.0-rc5-next-20200515 #1
NIP:  c0660c7c LR: c0660c44 CTR: c0660c2c
REGS: c1223e68 TRAP: 0700   Tainted: G        W          (5.7.0-rc5-next-20200515)
MSR:  00021000 <CE,ME>  CR: 28000224  XER: 20000000

GPR00: c0669c78 c1223f20 c113d560 c0660c44 00000000 00000001 c1223ea8 00000001
GPR08: 00000000 00000001 0000fffc ffffffff 88000222 00000000 00000000 00000000
GPR16: 00000000 00000000 00000000 00000000 c0000000 00000000 00000000 c1125084
GPR24: c1125084 c1230000 c1879538 fffffffc 00000001 00000000 c1011afc c1230000
NIP [c0660c7c] irqsafe1_hard_spin_12+0x50/0xb0
LR [c0660c44] irqsafe1_hard_spin_12+0x18/0xb0
Call Trace:
[c1223f20] [c1880000] megasas_mgmt_info+0xee4/0x1008 (unreliable)
[c1223f40] [c0669c78] dotest+0x38/0x550
[c1223f70] [c066aa4c] locking_selftest+0x8bc/0x1d54
[c1223fa0] [c10e0bc8] start_kernel+0x3ec/0x510
[c1223ff0] [c00003a0] set_ivor+0x118/0x154
Instruction dump:
81420000 38e80001 3d4a0001 2c080000 91420000 90e20488 40820008 91020470
81290000 5529031e 7d290034 5529d97e <0f090000> 3fe0c11c 3bff3964 3bff00ac
irq event stamp: 588
hardirqs last  enabled at (587): [<c00b9fe4>] vprintk_emit+0x1b4/0x33c
hardirqs last disabled at (588): [<c0660c44>] irqsafe1_hard_spin_12+0x18/0xb0
softirqs last  enabled at (0): [<00000000>] 0x0
softirqs last disabled at (0): [<00000000>] 0x0
---[ end trace b18fe9e172f99d03 ]---

This is followed by:

BUG: sleeping function called from invalid context at lib/mpi/mpi-pow.c:245
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 14, name: cryptomgr_test
INFO: lockdep is turned off.
CPU: 0 PID: 14 Comm: cryptomgr_test Tainted: G        W         5.7.0-rc5-next-20200515 #1
Call Trace:
[ce221b58] [c008755c] ___might_sleep+0x280/0x2a8 (unreliable)
[ce221b78] [c06bc524] mpi_powm+0x634/0xc50
[ce221c38] [c05eafdc] rsa_dec+0x88/0x134
[ce221c78] [c05f3b40] test_akcipher_one+0x678/0x804
[ce221dc8] [c05f3d7c] alg_test_akcipher+0xb0/0x130
[ce221df8] [c05ee674] alg_test.part.0+0xb4/0x458
[ce221ed8] [c05ed2b0] cryptomgr_test+0x30/0x50
[ce221ef8] [c007cd74] kthread+0x134/0x170
[ce221f38] [c001433c] ret_from_kernel_thread+0x14/0x1c
Kernel panic - not syncing: Aiee, killing interrupt handler!
CPU: 0 PID: 14 Comm: cryptomgr_test Tainted: G        W         5.7.0-rc5-next-20200515 #1
Call Trace:
[ce221e08] [c00530fc] panic+0x148/0x34c (unreliable)
[ce221e68] [c0056460] do_exit+0xac0/0xb40
[ce221eb8] [c00f5be8] find_kallsyms_symbol_value+0x0/0x128
[ce221ed8] [c05ed2d0] crypto_alg_put+0x0/0x70
[ce221ef8] [c007cd74] kthread+0x134/0x170
[ce221f38] [c001433c] ret_from_kernel_thread+0x14/0x1c

Bisect log is attached. The patch can not easily be reverted since
it results in compile errors.

Note that similar failures are seen with sparc32 images. Those bisect
to a different patch, but reverting that patch doesn't fix the problem.
The failure pattern (warnings followed by a crash in cryptomgr_test)
is the same.

Guenter

---
# bad: [bdecf38f228bcca73b31ada98b5b7ba1215eb9c9] Add linux-next specific files for 20200515
# good: [2ef96a5bb12be62ef75b5828c0aab838ebb29cb8] Linux 5.7-rc5
git bisect start 'HEAD' 'v5.7-rc5'
# good: [3674d7aa7a8e61d993886c2fb7c896c5ef85e988] Merge remote-tracking branch 'crypto/master'
git bisect good 3674d7aa7a8e61d993886c2fb7c896c5ef85e988
# good: [87f6f21783522e6d62127cf33ae5e95f50874beb] Merge remote-tracking branch 'spi/for-next'
git bisect good 87f6f21783522e6d62127cf33ae5e95f50874beb
# good: [5c428e8277d5d97c85126387d4e00aa5adde4400] Merge remote-tracking branch 'staging/staging-next'
git bisect good 5c428e8277d5d97c85126387d4e00aa5adde4400
# good: [f68de67ed934e7bdef4799fd7777c86f33f14982] Merge remote-tracking branch 'hyperv/hyperv-next'
git bisect good f68de67ed934e7bdef4799fd7777c86f33f14982
# bad: [54acd2dc52b069da59639eea0d0c92726f32fb01] mm/memblock: fix a typo in comment "implict"->"implicit"
git bisect bad 54acd2dc52b069da59639eea0d0c92726f32fb01
# good: [784a17aa58a529b84f7cc50f351ed4acf3bd11f3] mm: remove the pgprot argument to __vmalloc
git bisect good 784a17aa58a529b84f7cc50f351ed4acf3bd11f3
# good: [6cd8137ff37e9a37aee2d2a8889c8beb8eab192f] khugepaged: replace the usage of system(3) in the test
git bisect good 6cd8137ff37e9a37aee2d2a8889c8beb8eab192f
# bad: [6987da379826ed01b8a1cf046b67cc8cc10117cc] sparc: remove unnecessary includes
git bisect bad 6987da379826ed01b8a1cf046b67cc8cc10117cc
# good: [bc17b545388f64c09e83e367898e28f60277c584] mm/hugetlb: define a generic fallback for is_hugepage_only_range()
git bisect good bc17b545388f64c09e83e367898e28f60277c584
# good: [9b5aa5b43f957f03a1f4a9aff5f7924e2ebbc011] arch-kmap_atomic-consolidate-duplicate-code-checkpatch-fixes
git bisect good 9b5aa5b43f957f03a1f4a9aff5f7924e2ebbc011
# bad: [89194ba5ee31567eeee9c81101b334c8e3248198] arch/kmap: define kmap_atomic_prot() for all arch's
git bisect bad 89194ba5ee31567eeee9c81101b334c8e3248198
# good: [022785d2bea99f8bc2a37b7b6c525eea26f6ac59] arch-kunmap_atomic-consolidate-duplicate-code-checkpatch-fixes
git bisect good 022785d2bea99f8bc2a37b7b6c525eea26f6ac59
# good: [a13c2f39e3f0519ddee57d26cc66ec70e3546106] arch/kmap: don't hard code kmap_prot values
git bisect good a13c2f39e3f0519ddee57d26cc66ec70e3546106
# first bad commit: [89194ba5ee31567eeee9c81101b334c8e3248198] arch/kmap: define kmap_atomic_prot() for all arch's

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