properly detect no changed objects #57
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The current solution doesn't work because "$?" will always be 0, even if there were no "CC" lines in the build log. Instead, just make sure the changed_objs file isn't empty.
sjenning
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Mar 13, 2014
properly detect no changed objects
sjenning
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in jpoimboe/kpatch
Mar 19, 2014
Now that we don't need to track module dependencies anymore, remove the module argument from kpatch_[un]register.
jpoimboe
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Mar 23, 2023
Yulia reported a bug with module.patch which can be seen with
CONFIG_PROVE_RCU:
BUG: sleeping function called from invalid context at include/linux/percpu-rwsem.h:49
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1053, name: grep
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
2 locks held by grep/1053:
#0: ffff8881079bf1a0 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x55/0x460
dynup#1: ffffffff8275d620 (rcu_read_lock){....}-{1:2}, at: cache_seq_start_rcu+0x5/0x140 [sunrpc]
CPU: 3 PID: 1053 Comm: grep Tainted: G OE K 6.2.0 dynup#57
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x5b/0x77
__might_resched.cold+0xff/0x13a
cpus_read_lock+0x16/0xd0
static_key_disable+0xe/0x20
e_show+0x5b/0xd70 [livepatch_module]
seq_read_iter+0x127/0x460
seq_read+0xa3/0xd0
proc_reg_read+0x52/0xa0
vfs_read+0xc9/0x2f0
? __do_sys_newfstat+0x57/0x60
? lock_is_held_type+0xe8/0x140
ksys_read+0x6c/0xf0
do_syscall_64+0x37/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
RIP: 0033:0x7fbd314f7af0
Code: b6 fe ff ff 48 8d 3d 2f 78 09 00 48 83 ec 08 e8 96 25 02 00 66 0f 1f 44 00 00 83 3d d9 db 2c 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 7e e3 01 00 48 89 04 24
RSP: 002b:00007ffcd6f1c708 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000008000 RCX: 00007fbd314f7af0
RDX: 0000000000008000 RSI: 0000563c751ea000 RDI: 0000000000000003
RBP: 0000000000008000 R08: 0000000000009008 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000563c751ea000
R13: 0000000000000003 R14: 0000000000000003 R15: 0000563c751ea000
The problem is that the patched module's seq_operations take an RCU read
lock before calling e_show(), which is patched to call
static_key_disable(), which can sleep.
Fix the issue by moving all the module test code to a different module
(xfs) which doesn't take an RCU lock.
Also enable the pr_debug() test and make the static branch test
unconditional since they're supported by newer kernels and this test is
for 6.2.
Reported-by: Yulia Kopkova <ykopkova@redhat.com>
Debugged-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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The current solution doesn't work because "$?" will always be 0, even if
there were no "CC" lines in the build log. Instead, just make sure the
changed_objs file isn't empty.