Re: [PATCH v3 31/41] powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE
From: Christophe Leroy
Date: Sat Jul 31 2021 - 12:35:41 EST
Finn Thain <fthain@xxxxxxxxxxxxxx> a écrit :
Hi Christophe,
We found that reducing memory with the kernel parameter 'mem=464M' would
prevent the crash.
Below are Stan's notes from the 'git bisect' run. They include an
additional failure mode that might be of interest. We've also observed
"Kernel attempted to write user page (c6207c) - exploit attempt?" and
"kernel BUG at arch/powerpc/kernel/interrupt.c:49!".
Interesting. Can you provide detailed log of thoose two BUGs ?
Thanks
Christophe
On Thu, 29 Jul 2021, Stanley J. Johnson wrote:
Here are the git bisect results (I saved the kernels and dmesg outputs
in case they're needed later, though it's easy enough to re-create the
results).
We'll have up to two boots (only one if the first boot fails) for each
kernel on WS-1 with the default memory setting of 512M.
1) 5.12.0-pmac-08447-g85f3f17b5db (good)
-> works: no dmesg errs, X works
-> works: no dmesg errs, X works
2) 5.12.0-pmac-12750-g23243c1ace9 (bad)
(Crash and burn. I was tempted to mark this one "skip", since the errors
are different, though we've seen them in earlier tests. So there could
be multiple regressions. But let's keep chasing this one. I can re-run
the bisect later and skip some failures if necessary.)
-> fails: "Unable to contact settings server" after wdm login; dmesg errors:
...
[ 127.169294] BUG: Unable to handle kernel instruction fetch (NULL
pointer?)
[ 127.169397] Faulting instruction address: 0x00000000
[ 127.169635] Oops: Kernel access of bad area, sig: 11 [#2]
[ 127.169661] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 127.169696] Modules linked in:
[ 127.169736] CPU: 0 PID: 1877 Comm: gdbus Tainted: G D
5.12.0-pmac-12750-g23243c1ace9 #9
[ 127.169776] NIP: 00000000 LR: 00000000 CTR: 00000000
...
3) 5.12.0-rc7-pmac-02335-gaeacb52a8de (good)
-> works: no dmesg errs, X works
-> works: no dmesg errs, X works
4) 5.12.0-pmac-11585-g95275402f66 (bad)
-> fails: dmesg errs, wdm login fails with "Unable to contact settings
server..."
...
[ 58.290883] BUG: Unable to handle kernel instruction fetch
[ 58.291009] Faulting instruction address: 0x7cc903a4
[ 58.291240] Oops: Kernel access of bad area, sig: 11 [#1]
[ 58.291268] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 58.291305] Modules linked in:
[ 58.291349] CPU: 0 PID: 1750 Comm: Xorg Not tainted
5.12.0-pmac-11585-g95275402f66 #11
[ 58.291391] NIP: 7cc903a4 LR: 7cc903a6 CTR: c0127eb8
[ 58.291417] REGS: e2da1e70 TRAP: 0400 Not tainted
(5.12.0-pmac-11585-g95275402f66)
[ 58.291450] MSR: 40001030 <ME,IR,DR> CR: 28008228 XER: 20000000
...
5) 5.12.0-pmac-11068-g9d31d233895 (good)
-> works: no dmesg errs, X works
-> works: no dmesg errs, X works
6) 5.12.0-rc3-pmac-00258-ga9d2f9bb225 (bad)
-> fails: wdm dies at login, screen hangs, dmesg errs that I haven't
seen before:
...
[ 59.988732] InputThread[1751]: bad frame in sys_rt_sigreturn:
51a79ab6 nip 001023c8 lr 001023c0
[ 62.079043] InputThread[1760]: bad frame in sys_rt_sigreturn:
a98be235 nip 001023c8 lr 001023c0
[ 64.348063] InputThread[1776]: bad frame in sys_rt_sigreturn:
a46b945e nip 001023c8 lr 001023c0
[ 66.413980] InputThread[1785]: bad frame in sys_rt_sigreturn:
a98be235 nip 001023c8 lr 001023c0
[ 68.486768] InputThread[1794]: bad frame in sys_rt_sigreturn:
677e693b nip 001023c8 lr 001023c0
7) 5.12.0-rc3-pmac-00129-g036fc2cb1dc (bad)
-> fails: dmesg errs, wdm hangs (wdm did not crash, screen seems hung)
...
[ 101.136941] BUG: Unable to handle kernel instruction fetch
[ 101.137059] Faulting instruction address: 0xfea31f74
[ 101.137296] Oops: Kernel access of bad area, sig: 11 [#1]
[ 101.137323] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 101.137358] Modules linked in:
[ 101.137401] CPU: 0 PID: 1882 Comm: xfce4-session Not tainted
5.12.0-rc3-pmac-00129-g036fc2cb1dc #14
[ 101.137443] NIP: fea31f74 LR: fea31f74 CTR: c00cfef4
[ 101.137470] REGS: e2e21e70 TRAP: 0400 Not tainted
(5.12.0-rc3-pmac-00129-g036fc2cb1dc)
[ 101.137502] MSR: 40001030 <ME,IR,DR> CR: 220084e8 XER: 00000000
...
8) 5.12.0-rc3-pmac-00064-g719e7e212c7 (good)
-> works: no dmesg errs, X works
-> works: no dmesg errs, X works
9) 5.12.0-rc3-pmac-00096-ga2308836880 (bad)
-> fails: dmesg errs, wdm hangs while validating login
...
[ 104.559951] BUG: Unable to handle kernel instruction fetch
[ 104.560086] Faulting instruction address: 0xfe988ba4
[ 104.560307] Oops: Kernel access of bad area, sig: 11 [#1]
[ 104.560337] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 104.560371] Modules linked in:
[ 104.560415] CPU: 0 PID: 1834 Comm: xfce4-session Not tainted
5.12.0-rc3-pmac-00096-ga2308836880 #16
[ 104.560457] NIP: fe988ba4 LR: fe988ba4 CTR: c00cfee8
[ 104.560484] REGS: e2d9de70 TRAP: 0400 Not tainted
(5.12.0-rc3-pmac-00096-ga2308836880)
[ 104.560517] MSR: 40001030 <ME,IR,DR> CR: 220484e8 XER: 00000000
...
[ 114.371853] BUG: Unable to handle kernel instruction fetch
[ 114.371998] Faulting instruction address: 0x3e62a270
[ 114.372270] Oops: Kernel access of bad area, sig: 11 [#2]
[ 114.372298] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 114.372334] Modules linked in:
[ 114.372382] CPU: 0 PID: 1858 Comm: xfwm4 Tainted: G D
5.12.0-rc3-pmac-00096-ga2308836880 #16
[ 114.372425] NIP: 3e62a270 LR: 3e62a271 CTR: c065eebc
[ 114.372452] REGS: e2dede70 TRAP: 0400 Tainted: G D
(5.12.0-rc3-pmac-00096-ga2308836880)
[ 114.372486] MSR: 40001030 <ME,IR,DR> CR: 22002284 XER: 00000000
...
10) 5.12.0-rc3-pmac-00080-g7a7d744ffe8 (bad)
-> fails: dmesg errs, "Unable to contact settings server..."
...
[ 170.622408] BUG: Unable to handle kernel instruction fetch
[ 170.622546] Faulting instruction address: 0xfe9255d4
[ 170.622777] Oops: Kernel access of bad area, sig: 11 [#1]
[ 170.622806] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 170.622841] Modules linked in:
[ 170.622885] CPU: 0 PID: 1863 Comm: xfce4-session Not tainted
5.12.0-rc3-pmac-00080-g7a7d744ffe8 #17
[ 170.622927] NIP: fe9255d4 LR: fe9255d4 CTR: c00cfee8
[ 170.622954] REGS: e2da1e70 TRAP: 0400 Not tainted
(5.12.0-rc3-pmac-00080-g7a7d744ffe8)
[ 170.622987] MSR: 40001030 <ME,IR,DR> CR: 220484e8 XER: 00000000
...
[ 172.611235] BUG: Unable to handle kernel instruction fetch (NULL
pointer?)
[ 172.611364] Faulting instruction address: 0x00000000
[ 172.611662] Oops: Kernel access of bad area, sig: 11 [#2]
[ 172.611690] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
[ 172.611725] Modules linked in:
[ 172.611773] CPU: 0 PID: 1871 Comm: gmain Tainted: G D
5.12.0-rc3-pmac-00080-g7a7d744ffe8 #17
[ 172.611814] NIP: 00000000 LR: 00000000 CTR: 00000000
[ 172.611840] REGS: e2db9e70 TRAP: 0400 Tainted: G D
(5.12.0-rc3-pmac-00080-g7a7d744ffe8)
[ 172.611874] MSR: 40001030 <ME,IR,DR> CR: 28008468 XER: 00000000
...
11) 5.12.0-rc3-pmac-00072-ga2b3e09ae41 (bad)
-> fails: kernel panic, I'd have to capture the output via a serial console
12) 5.12.0-rc3-pmac-00068-gacc142b6230 (bad)
-> fails: kernel panic
13) 5.12.0-rc3-pmac-00066-g8f6ff5bd9b7 (good)
-> works: no dmesg errs, X works
-> works: no dmesg errs, X works
14) 5.12.0-rc3-pmac-00067-g4c0104a83fc (bad)
-> fails: kernel panic
The git bisect thinks this is the bad commit, but I'm not sure it means
anything at all:
-----
4c0104a83fc3990a76a01a2f4e504251fa9814c4 is the first bad commit