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 <[email protected]> Link: https://lore.kernel.org/linux-mm/[email protected] Cc: Suren Baghdasaryan <[email protected]> Signed-off-by: Laurent Dufour <[email protected]> --- 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.
-- Thanks, David / dhildenb
