On Mon, Jun 03, 2019 at 12:11:22PM +0530, Anshuman Khandual wrote: > There is an inconsistency between down_read_trylock() success and failure > paths while dealing with kernel access for non exception table areas where > it calls __do_kernel_fault(). In case of failure it just bails out without > holding mmap_sem but when it succeeds it does so while holding mmap_sem. > Fix this inconsistency by just dropping mmap_sem in success path as well. > > __do_kernel_fault() calls die_kernel_fault() which then calls show_pte(). > show_pte() in this path might become bit more unreliable without holding > mmap_sem. But there are already instances [1] in do_page_fault() where > die_kernel_fault() gets called without holding mmap_sem. show_pte() can > be made more robust independently but in a later patch. > > [1] Conditional block for (is_ttbr0_addr && is_el1_permission_fault) > > Signed-off-by: Anshuman Khandual <anshuman.khand...@arm.com> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: Will Deacon <will.dea...@arm.com> > Cc: Mark Rutland <mark.rutl...@arm.com> > Cc: James Morse <james.mo...@arm.com> > Cc: Andrey Konovalov <andreyk...@google.com>
Queued for 5.3. Thanks. -- Catalin
