| Message ID | 20241130115355.3316160-1-guoren@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | riscv: Fixup boot failure when CONFIG_RT_MUTEXES=y | expand |
On Sat, Nov 30, 2024 at 7:54 PM <guoren@kernel.org> wrote: > > From: Guo Ren <guoren@linux.alibaba.com> > > When CONFIG_RT_MUTEXES=y, mutex_lock->rt_mutex_try_acquire would Correct: CONFIG_DEBUG_RT_MUTEXES=y > change from rt_mutex_cmpxchg_acquire to rt_mutex_slowtrylock(): > raw_spin_lock_irqsave(&lock->wait_lock, flags); > ret = __rt_mutex_slowtrylock(lock); > raw_spin_unlock_irqrestore(&lock->wait_lock, flags); > > Because queued_spin_#ops to ticket_#ops is changed one by one by > jump_label, raw_spin_lock/unlock would cause a deadlock during the > changing. > > That means in arch/riscv/kernel/jump_label.c: > 1. > arch_jump_label_transform_queue() -> > mutex_lock(&text_mutex); +-> raw_spin_lock -> queued_spin_lock > |-> raw_spin_unlock -> queued_spin_unlock > patch_insn_write -> change the raw_spin_lock to ticket_lock > mutex_unlock(&text_mutex); > ... > > 2. /* Dirty the lock value */ > arch_jump_label_transform_queue() -> > mutex_lock(&text_mutex); +-> raw_spin_lock -> *ticket_lock* > |-> raw_spin_unlock -> *queued_spin_unlock* > /* BUG: ticket_lock with queued_spin_unlock */ > patch_insn_write -> change the raw_spin_unlock to ticket_unlock > mutex_unlock(&text_mutex); > ... > > 3. /* Dead lock */ > arch_jump_label_transform_queue() -> > mutex_lock(&text_mutex); +-> raw_spin_lock -> ticket_lock /* deadlock! */ > |-> raw_spin_unlock -> ticket_unlock > patch_insn_write -> change other raw_spin_#op -> ticket_#op > mutex_unlock(&text_mutex); > > So, the solution is to disable mutex usage of > arch_jump_label_transform_queue() during early_boot_irqs_disabled, just > like we have done for stop_machine. > > Reported-by: Conor Dooley <conor@kernel.org> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> > Signed-off-by: Guo Ren <guoren@kernel.org> > Fixes: ab83647fadae ("riscv: Add qspinlock support") > Link: https://lore.kernel.org/linux-riscv/CAJF2gTQwYTGinBmCSgVUoPv0_q4EPt_+WiyfUA1HViAKgUzxAg@mail.gmail.com/T/#mf488e6347817fca03bb93a7d34df33d8615b3775 > Cc: Palmer Dabbelt <palmer@dabbelt.com> > Cc: Alexandre Ghiti <alexghiti@rivosinc.com> > --- > arch/riscv/kernel/jump_label.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c > index 6eee6f736f68..654ed159c830 100644 > --- a/arch/riscv/kernel/jump_label.c > +++ b/arch/riscv/kernel/jump_label.c > @@ -36,9 +36,15 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry, > insn = RISCV_INSN_NOP; > } > > - mutex_lock(&text_mutex); > - patch_insn_write(addr, &insn, sizeof(insn)); > - mutex_unlock(&text_mutex); > + if (early_boot_irqs_disabled) { > + riscv_patch_in_stop_machine = 1; > + patch_insn_write(addr, &insn, sizeof(insn)); > + riscv_patch_in_stop_machine = 0; > + } else { > + mutex_lock(&text_mutex); > + patch_insn_write(addr, &insn, sizeof(insn)); > + mutex_unlock(&text_mutex); > + } > > return true; > } > -- > 2.40.1 >
On Sat, Nov 30, 2024 at 8:02 PM Guo Ren <guoren@kernel.org> wrote: > > On Sat, Nov 30, 2024 at 7:54 PM <guoren@kernel.org> wrote: > > > > From: Guo Ren <guoren@linux.alibaba.com> > > > > When CONFIG_RT_MUTEXES=y, mutex_lock->rt_mutex_try_acquire would > Correct: CONFIG_DEBUG_RT_MUTEXES=y Abandoned. Here is the RESEND PATCH: https://lore.kernel.org/linux-riscv/20241130153310.3349484-1-guoren@kernel.org/ > > > change from rt_mutex_cmpxchg_acquire to rt_mutex_slowtrylock(): > > raw_spin_lock_irqsave(&lock->wait_lock, flags); > > ret = __rt_mutex_slowtrylock(lock); > > raw_spin_unlock_irqrestore(&lock->wait_lock, flags); > > > > Because queued_spin_#ops to ticket_#ops is changed one by one by > > jump_label, raw_spin_lock/unlock would cause a deadlock during the > > changing. > > > > That means in arch/riscv/kernel/jump_label.c: > > 1. > > arch_jump_label_transform_queue() -> > > mutex_lock(&text_mutex); +-> raw_spin_lock -> queued_spin_lock > > |-> raw_spin_unlock -> queued_spin_unlock > > patch_insn_write -> change the raw_spin_lock to ticket_lock > > mutex_unlock(&text_mutex); > > ... > > > > 2. /* Dirty the lock value */ > > arch_jump_label_transform_queue() -> > > mutex_lock(&text_mutex); +-> raw_spin_lock -> *ticket_lock* > > |-> raw_spin_unlock -> *queued_spin_unlock* > > /* BUG: ticket_lock with queued_spin_unlock */ > > patch_insn_write -> change the raw_spin_unlock to ticket_unlock > > mutex_unlock(&text_mutex); > > ... > > > > 3. /* Dead lock */ > > arch_jump_label_transform_queue() -> > > mutex_lock(&text_mutex); +-> raw_spin_lock -> ticket_lock /* deadlock! */ > > |-> raw_spin_unlock -> ticket_unlock > > patch_insn_write -> change other raw_spin_#op -> ticket_#op > > mutex_unlock(&text_mutex); > > > > So, the solution is to disable mutex usage of > > arch_jump_label_transform_queue() during early_boot_irqs_disabled, just > > like we have done for stop_machine. > > > > Reported-by: Conor Dooley <conor@kernel.org> > > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> > > Signed-off-by: Guo Ren <guoren@kernel.org> > > Fixes: ab83647fadae ("riscv: Add qspinlock support") > > Link: https://lore.kernel.org/linux-riscv/CAJF2gTQwYTGinBmCSgVUoPv0_q4EPt_+WiyfUA1HViAKgUzxAg@mail.gmail.com/T/#mf488e6347817fca03bb93a7d34df33d8615b3775 > > Cc: Palmer Dabbelt <palmer@dabbelt.com> > > Cc: Alexandre Ghiti <alexghiti@rivosinc.com> > > --- > > arch/riscv/kernel/jump_label.c | 12 +++++++++--- > > 1 file changed, 9 insertions(+), 3 deletions(-) > > > > diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c > > index 6eee6f736f68..654ed159c830 100644 > > --- a/arch/riscv/kernel/jump_label.c > > +++ b/arch/riscv/kernel/jump_label.c > > @@ -36,9 +36,15 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry, > > insn = RISCV_INSN_NOP; > > } > > > > - mutex_lock(&text_mutex); > > - patch_insn_write(addr, &insn, sizeof(insn)); > > - mutex_unlock(&text_mutex); > > + if (early_boot_irqs_disabled) { > > + riscv_patch_in_stop_machine = 1; > > + patch_insn_write(addr, &insn, sizeof(insn)); > > + riscv_patch_in_stop_machine = 0; > > + } else { > > + mutex_lock(&text_mutex); > > + patch_insn_write(addr, &insn, sizeof(insn)); > > + mutex_unlock(&text_mutex); > > + } > > > > return true; > > } > > -- > > 2.40.1 > > > > > -- > Best Regards > Guo Ren
diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c index 6eee6f736f68..654ed159c830 100644 --- a/arch/riscv/kernel/jump_label.c +++ b/arch/riscv/kernel/jump_label.c @@ -36,9 +36,15 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry, insn = RISCV_INSN_NOP; } - mutex_lock(&text_mutex); - patch_insn_write(addr, &insn, sizeof(insn)); - mutex_unlock(&text_mutex); + if (early_boot_irqs_disabled) { + riscv_patch_in_stop_machine = 1; + patch_insn_write(addr, &insn, sizeof(insn)); + riscv_patch_in_stop_machine = 0; + } else { + mutex_lock(&text_mutex); + patch_insn_write(addr, &insn, sizeof(insn)); + mutex_unlock(&text_mutex); + } return true; }