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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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a0509313d5
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.khandual@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
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