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Subject[PATCH] x86, syscall: Fix _TIF_NOHZ handling in syscall_trace_enter_phase1
Date
TIF_NOHZ is 19 (i.e. _TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME |
_TIF_SINGLESTEP), not (1<<19).

This code is involved in Dave's trinity lockup, but I don't see why
it would cause any of the problems he's seeing, except inadvertently
by causing a different path through entry_64.S's syscall handling.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
arch/x86/kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 749b0e423419..e510618b2e91 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1484,7 +1484,7 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
*/
if (work & _TIF_NOHZ) {
user_exit();
- work &= ~TIF_NOHZ;
+ work &= ~_TIF_NOHZ;
}

#ifdef CONFIG_SECCOMP
--
1.9.3


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