Messages in this thread | | | Date | Mon, 6 Mar 2023 15:07:26 +0100 | Subject | Re: [PATCH] powerpc/mm: fix mmap_lock bad unlock | From | David Hildenbrand <> |
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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@linux.ibm.com> > Link: https://lore.kernel.org/linux-mm/842502FB-F99C-417C-9648-A37D0ECDC9CE@linux.ibm.com > Cc: Suren Baghdasaryan <surenb@google.com> > Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> > --- > 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
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