ad1754318c [ 7.413021] kernel BUG at include/linux/gfp.h:466!

Tuesday, 31 July 2018


Greetings,

0day kernel testing robot got the below dmesg and the first bad commit is

https://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git
siginfo-testing

commit ad1754318cc4dab034d959fcc8e2c34dec0e3d82
Author:     Eric W. Biederman <ebiederm(a)xmission.com&gt;
AuthorDate: Mon Jul 23 15:20:37 2018 -0500
Commit:     Eric W. Biederman <ebiederm(a)xmission.com&gt;
CommitDate: Tue Jul 24 16:26:33 2018 -0500

    signal: Don't restart fork when signals come in.
    
    Wen Yang <wen.yang99(a)zte.com.cn&gt; and majiang <ma.jiang(a)zte.com.cn&gt;
    report that a periodic signal received during fork can cause fork to
    continually restart preventing an application from making progress.
    
    The code was being overly pesimistic.  Fork needs to guarantee that a
    signal sent to multiple processes is logically delivered before the
    fork and just to the forking process or logically delivered after the
    fork to both the forking process and it's newly spawned child.  For
    signals like periodic timers that are always delivered to a single
    process fork can safely complete and let them appear to logically
    delivered after the fork().
    
    While examining this issue I also discovered that fork today will miss
    signals delivered to multiple processes during the fork and handled by
    another thread.  Similarly the current code will also miss blocked
    signals that are delivered to multiple process, as those signals will
    not appear pending during fork.
    
    Add a list of each thread that is currently forking, and keep on that
    list a signal set that records all of the signals sent to multiple
    processes.  When fork completes initialize the new processes
    shared_pending signal set with it.  The calculate_sigpending function
    will see those signals and set TIF_SIGPENDING causing the new task to
    take the slow path to userspace to handle those signals.  Making it
    appear as if those signals were received immediately after the fork.
    
    It is not possible to send real time signals to multiple processes and
    exceptions don't go to multiple processes, which means that that are
    no signals sent to multiple processes that require siginfo.  This
    means it is safe to not bother collecting siginfo on signals sent
    during fork.
    
    The sigaction of a child of fork is initially the same as the
    sigaction of the parent process.  So a signal the parent ignores the
    child will also initially ignore.  Therefore it is safe to ignore
    signals sent to multiple processes and ignored by the forking process.
    
    Signals sent to only a single process or only a single thread and delivered
    during fork are treated as if they are received after the fork, and generally
    not dealt with.  They won't cause any problems.
    
    V2: Added removal from the multiprocess list on failure.
    V3: Use -ERESTARTNOINTR directly
    
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200447
    Reported-by: Wen Yang <wen.yang99(a)zte.com.cn&gt; and
    Reported-by: majiang <ma.jiang(a)zte.com.cn&gt;
    Fixes: 4a2c7a7837da ("[PATCH] make fork() atomic wrt pgrp/session signals")
    Signed-off-by: "Eric W. Biederman" <ebiederm(a)xmission.com&gt;

159fb05651  fork: Have new threads join on-going signal group stops
ad1754318c  signal: Don't restart fork when signals come in.
+------------------------------------------+------------+------------+
|                                          | 159fb05651 | ad1754318c |
+------------------------------------------+------------+------------+
| boot_successes                           | 35         | 2          |
| boot_failures                            | 0          | 13         |
| kernel_BUG_at_include/linux/gfp.h        | 0          | 13         |
| invalid_opcode:#[##]                     | 0          | 13         |
| RIP:copy_process                         | 0          | 13         |
| Kernel_panic-not_syncing:Fatal_exception | 0          | 13         |
+------------------------------------------+------------+------------+

[    7.379068] Freeing unused kernel memory: 188K
[    7.397925] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[    7.399618] rodata_test: all tests were successful
[    7.409207] random: init: uninitialized urandom read (12 bytes read)
[    7.411666] ------------[ cut here ]------------
[    7.413021] kernel BUG at include/linux/gfp.h:466!
[    7.414818] invalid opcode: 0000 [#1] PREEMPT SMP
[    7.416134] CPU: 1 PID: 1 Comm: init Not tainted 4.18.0-rc1-00020-gad17543 #1
[    7.417936] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1
04/01/2014
[    7.420211] RIP: 0010:copy_process+0x7cc/0x1bb0
[    7.421485] Code: 8b 3d 90 d5 7e 01 be c0 00 60 00 89 45 18 e8 fb 3f 13 00 48 85 c0 49
89 c4 74 cf 83 7d 18 ff 0f 84 5e fa ff ff e9 4e fa ff ff <0f> 0b 4c 89 e7 e8 1a 53
0d 00 85 c0 0f 85 7a fe ff ff 48 89 de 4c 
[    7.426166] RSP: 0018:ffff88000fc6bd68 EFLAGS: 00010206
[    7.427570] RAX: 000000000fc6be18 RBX: 0000000001200011 RCX: 0000000000000000
[    7.429373] RDX: 0000000000000000 RSI: 000000000000005a RDI: ffff88001fd83e80
[    7.431164] RBP: ffff88000fc6be50 R08: 0000000000000004 R09: 0000000000000000
[    7.432960] R10: ffff88001fd81000 R11: 0000000000000000 R12: ffff88001fd81000
[    7.434752] R13: 00007efc763c49d0 R14: 0000000000000000 R15: 0000000000000000
[    7.436535] FS:  00007efc763c4700(0000) GS:ffff88001d600000(0000)
knlGS:0000000000000000
[    7.438753] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    7.440258] CR2: 00007efc763c9000 CR3: 000000001f1e6000 CR4: 00000000000006a0
[    7.442055] Call Trace:
[    7.442902]  ? kvm_sched_clock_read+0x9/0x20
[    7.444113]  ? kvm_clock_read+0x25/0x40
[    7.445259]  ? kvm_sched_clock_read+0x9/0x20
[    7.446477]  _do_fork+0xa5/0x3f0
[    7.447484]  ? __might_sleep+0x50/0x90
[    7.448599]  ? __might_fault+0x29/0x30
[    7.449713]  ? _copy_to_user+0x66/0x80
[    7.450831]  __x64_sys_clone+0x22/0x30
[    7.451937]  do_syscall_64+0x5d/0x110
[    7.453041]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[    7.454404] RIP: 0033:0x7efc75420126
[    7.455475] Code: f7 d8 64 89 04 25 d4 02 00 00 64 4c 8b 0c 25 10 00 00 00 31 d2 4d 8d
91 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87
41 01 00 00 85 c0 41 89 c4 0f 85 4b 01 00 
[    7.460175] RSP: 002b:00007ffdd995e510 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
[    7.462308] RAX: ffffffffffffffda RBX: 00007ffdd995e510 RCX: 00007efc75420126
[    7.464099] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
[    7.465902] RBP: 00007ffdd995e570 R08: 0000000000000001 R09: 00007efc763c4700
[    7.467687] R10: 00007efc763c49d0 R11: 0000000000000246 R12: 0000000000000000
[    7.469488] R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
[    7.471275] Modules linked in:
[    7.472995] ---[ end trace 46857ad44e271661 ]---
[    7.474292] RIP: 0010:copy_process+0x7cc/0x1bb0

                                                          # HH:MM RESULT GOOD BAD
GOOD_BUT_DIRTY DIRTY_NOT_BAD
git bisect start 336f4d5a0cf9a9ef5714c8e73290820b1e4a7799
acb1872577b346bd15ab3a3f8dff780d6cca4b70 --
git bisect good db2c12af4e82ee2fa8e4d28ef17c0d62a234c6d0  # 16:45  G     11     0    0   0
 Merge
'linux-review/Gustavo-A-R-Silva/mailbox-xgene-slimpro-Fix-potential-NULL-pointer-dereference/20180728-160049'
into devel-hourly-2018073011
git bisect good 15146f5bf013d7dda5e95c74fc0da160362814e2  # 16:56  G     11     0    0   0
 Merge
'linux-review/Jia-Ju-Bai/net-nvidia-forcedeth-Replace-GFP_ATOMIC-with-GFP_KERNEL-in-nv_probe/20180728-012049'
into devel-hourly-2018073011
git bisect good 93328c4026996becf9d856e4ed74672f6e8e78b5  # 17:07  G     11     0    0   0
 Merge
'linux-review/Jia-Ju-Bai/video-fbdev-add-the-dependency-of-broadsheetfb-in-Kconfig/20180727-180657'
into devel-hourly-2018073011
git bisect good afd12c321712240fc66709000a6e6af17ffc0dfe  # 17:20  G     11     0    0   0
 Merge 'kvms390/hlp_vsie' into devel-hourly-2018073011
git bisect good c28736279a15d7753bac09ba667df00ce10322b5  # 17:37  G     11     0    0   0
 Merge 'kvm/master' into devel-hourly-2018073011
git bisect  bad 048cebf2bc43ba21ee23caa67a0c1756e5fc0de5  # 17:50  B      0     2   17   0
 Merge 'userns/siginfo-testing' into devel-hourly-2018073011
git bisect good 9eeaab07d31f43a3d0e2b3797e60df92b6e1c466  # 18:14  G     11     0    0   0
 Merge 'random/master' into devel-hourly-2018073011
git bisect good 3137667d9bbcba39db1090b6a7c2ea6ec3329ff6  # 18:23  G     11     0    0   0
 Merge 'hch-misc/net-poll-cleanup' into devel-hourly-2018073011
git bisect good 0102498083d58d8b17759642c602b525215e1a54  # 18:36  G     11     0    0   0
 signal: Pass pid type into group_send_sig_info
git bisect good 0729614992c946f6e8ccb9ef260aea1f06993df0  # 18:45  G     11     0    0   0
 signal: Push pid type down into complete_signal.
git bisect good 73ce6fe330cf55ee1b7de4bcdc6e0706f1ee436c  # 18:58  G     11     0    0   0
 signal: Add calculate_sigpending()
git bisect  bad ad1754318cc4dab034d959fcc8e2c34dec0e3d82  # 19:12  B      0     2   17   0
 signal: Don't restart fork when signals come in.
git bisect good 159fb056514ad8b1459128e8140ef6ce2af30478  # 19:26  G     11     0    0   0
 fork: Have new threads join on-going signal group stops
# first bad commit: [ad1754318cc4dab034d959fcc8e2c34dec0e3d82] signal: Don't restart
fork when signals come in.
git bisect good 159fb056514ad8b1459128e8140ef6ce2af30478  # 19:28  G     31     0    0   0
 fork: Have new threads join on-going signal group stops
# extra tests with debug options
git bisect  bad ad1754318cc4dab034d959fcc8e2c34dec0e3d82  # 19:38  B      0     1   16   0
 signal: Don't restart fork when signals come in.
# extra tests on HEAD of linux-devel/devel-hourly-2018073011
git bisect  bad 336f4d5a0cf9a9ef5714c8e73290820b1e4a7799  # 19:43  B      0   365  384   0
 0day head guard for 'devel-hourly-2018073011'
# extra tests on tree/branch userns/siginfo-testing
git bisect  bad ad1754318cc4dab034d959fcc8e2c34dec0e3d82  # 19:45  B      0    13   29   0
 signal: Don't restart fork when signals come in.
# extra tests with first bad commit reverted
git bisect good f6d9006c6389f5141f78c0f7ee0d31f9a0dcb2ad  # 19:55  G     11     0    0   0
 Revert "signal: Don't restart fork when signals come in."

---
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