On 6/20/25 13:09, Nam Cao wrote:

This reverts commit 61a74ad25462 ("riscv: misaligned: fix sleeping function called during misaligned access handling"). The commit addresses a sleeping in atomic context problem, but it is not the correct fix as explained by Clément:

"Using nofault would lead to failure to read from user memory that is paged out for instance. This is not really acceptable, we should handle user misaligned access even at an address that would generate a page fault."

This bug has been properly fixed by commit 453805f0a28f ("riscv: misaligned: enable IRQs while handling misaligned accesses").

Revert this improper fix.

Link: https://lore.kernel.org/linux-riscv/b779beed-e44e-4a5e-9551-4647682b0d21@riv... Signed-off-by: Nam Cao namcao@linutronix.de Cc: stable@vger.kernel.org

---

arch/riscv/kernel/traps_misaligned.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index dd8e4af6583f4..93043924fe6c6 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -454,7 +454,7 @@ static int handle_scalar_misaligned_load(struct pt_regs *regs) val.data_u64 = 0; if (user_mode(regs)) {

• if (copy_from_user_nofault(&val, (u8 __user *)addr, len))
  

• if (copy_from_user(&val, (u8 __user *)addr, len))
  return -1;
  

  } else { memcpy(&val, (u8 *)addr, len);

@@ -555,7 +555,7 @@ static int handle_scalar_misaligned_store(struct pt_regs *regs) return -EOPNOTSUPP; if (user_mode(regs)) {

• if (copy_to_user_nofault((u8 __user *)addr, &val, len))
  

• if (copy_to_user((u8 __user *)addr, &val, len))
  return -1;
  

  } else { memcpy((u8 *)addr, &val, len);

Of course this is a wrong fix:

Reviewed-by: Alexandre Ghiti alexghiti@rivosinc.com

Thanks for catching this,

Alex