Saw this warning again, and this time from the ret_from_fork path.
It seems we could clear the back chain earlier in copy_thread(), which
could cover both path, and also fix potential lockdep usage in
schedule_tail(), or exception occurred before we clear the back chain.
Signed-off-by: Li Zhong <zh...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/entry_32.S | 2 --
arch/powerpc/kernel/entry_64.S | 2 --
arch/powerpc/kernel/process.c | 1 +
3 files changed, 1 insertion(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index e514de5..d22e73e 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -439,8 +439,6 @@ ret_from_fork:
ret_from_kernel_thread:
REST_NVGPRS(r1)
bl schedule_tail
- li r3,0
- stw r3,0(r1)
mtlr r14
mr r3,r15
PPC440EP_ERR42
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 3fe5259..48e8a86 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -376,8 +376,6 @@ _GLOBAL(ret_from_fork)
_GLOBAL(ret_from_kernel_thread)
bl .schedule_tail
REST_NVGPRS(r1)
- li r3,0
- std r3,0(r1)
ld r14, 0(r14)
mtlr r14
mr r3,r15
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index ceb4e7b..80af366 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -971,6 +971,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
usp,
* do some house keeping and then return from the fork or clone
* system call, using the stack frame created above.
*/
+ ((unsigned long *)sp)[0] = 0;
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *) sp;
sp -= STACK_FRAME_OVERHEAD;
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