6.6-stable review patch. If anyone has any objections, please let me know.
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From: Gerald Schaefer gerald.schaefer@linux.ibm.com
commit df39038cd89525d465c2c8827eb64116873f141a upstream.
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_exception().
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_exception().
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@vger.kernel.org # 6.6+ Fixes: af19487f00f3 ("mm: make PTE_MARKER_SWAPIN_ERROR more general") Reported-by: Yunseong Kim yskelg@gmail.com Tested-by: Yunseong Kim yskelg@gmail.com Acked-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Gerald Schaefer gerald.schaefer@linux.ibm.com Message-ID: 20240715180416.3632453-1-gerald.schaefer@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Yunseong Kim yskelg@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/mm/fault.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -331,14 +331,16 @@ static noinline void do_fault_error(stru 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; } }