This patch backporting to v6.6.43+ cherry picked from commit df39038cd895 ("s390/mm: Fix VM_FAULT_HWPOISON handling in do_exception()") There is no support for HWPOISON, MEMORY_FAILURE, or ARCH_HAS_COPY_MC on s390. Therefore we do not expect to see VM_FAULT_HWPOISON in do_fault_error(). However, since commit af19487f00f3 ("mm: make PTE_MARKER_SWAPIN_ERROR more general"), it is possible to see VM_FAULT_HWPOISON in combination with PTE_MARKER_POISONED, even on architectures that do not support HWPOISON otherwise. In this case, we will end up on the BUG() in do_fault_error(). Fix this by treating VM_FAULT_HWPOISON the same as VM_FAULT_SIGBUS, similar to x86 when MEMORY_FAILURE is not configured. Also print unexpected fault flags, for easier debugging. Note that VM_FAULT_HWPOISON_LARGE is not expected, because s390 cannot support swap entries on other levels than PTE level. Cc: stable@xxxxxxxxxxxxxxx # 6.6+ Fixes: af19487f00f3 ("mm: make PTE_MARKER_SWAPIN_ERROR more general") Reported-by: Yunseong Kim <yskelg@xxxxxxxxx> Tested-by: Yunseong Kim <yskelg@xxxxxxxxx> Acked-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx> Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx> Message-ID: <20240715180416.3632453-1-gerald.schaefer@xxxxxxxxxxxxx> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> Signed-off-by: Yunseong Kim <yskelg@xxxxxxxxx> --- arch/s390/mm/fault.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index b678295931c3..1a231181a413 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -331,14 +331,16 @@ static noinline void do_fault_error(struct pt_regs *regs, vm_fault_t fault) do_no_context(regs, fault); else do_sigsegv(regs, SEGV_MAPERR); - } else if (fault & VM_FAULT_SIGBUS) { + } else if (fault & (VM_FAULT_SIGBUS | VM_FAULT_HWPOISON)) { /* Kernel mode? Handle exceptions or die */ if (!user_mode(regs)) do_no_context(regs, fault); else do_sigbus(regs); - } else + } else { + pr_emerg("Unexpected fault flags: %08x\n", fault); BUG(); + } break; } } -- 2.45.2