On 06/03/2023 15:07:26, David Hildenbrand wrote: > On 06.03.23 14:55, Laurent Dufour wrote: >> When page fault is tried holding the per VMA lock, bad_access_pkey() and >> bad_access() should not be called because it is assuming the mmap_lock is >> held. >> In the case a bad access is detected, fall back to the default path, >> grabbing the mmap_lock to handle the fault and report the error. >> >> Fixes: 169db3bb4609 ("powerc/mm: try VMA lock-based page fault handling >> first") >> Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxx> >> Link: >> https://lore.kernel.org/linux-mm/842502FB-F99C-417C-9648-A37D0ECDC9CE@xxxxxxxxxxxxx >> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> >> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx> >> --- >> arch/powerpc/mm/fault.c | 8 ++------ >> 1 file changed, 2 insertions(+), 6 deletions(-) >> >> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c >> index c7ae86b04b8a..e191b3ebd8d6 100644 >> --- a/arch/powerpc/mm/fault.c >> +++ b/arch/powerpc/mm/fault.c >> @@ -479,17 +479,13 @@ static int ___do_page_fault(struct pt_regs *regs, >> unsigned long address, >> if (unlikely(access_pkey_error(is_write, is_exec, >> (error_code & DSISR_KEYFAULT), vma))) { >> - int rc = bad_access_pkey(regs, address, vma); >> - >> vma_end_read(vma); >> - return rc; >> + goto lock_mmap; >> } >> if (unlikely(access_error(is_write, is_exec, vma))) { >> - int rc = bad_access(regs, address); >> - >> vma_end_read(vma); >> - return rc; >> + goto lock_mmap; >> } >> fault = handle_mm_fault(vma, address, flags | >> FAULT_FLAG_VMA_LOCK, regs); > > IIUC, that commit is neither upstream not in mm-stable -- it's unstable. > Maybe raise that as a review comment in reply to the original patch, so we > can easily connect the dots and squash it into the original, problematic > patch that is still under review. > Oh yes, I missed that. I'll reply to the Suren's thread. Thanks, Laurent.