Messages in this thread | | | From | Jann Horn <> | Date | Mon, 5 Oct 2020 03:30:43 +0200 | Subject | Re: [PATCH 1/2] mmap locking API: Order lock of nascent mm outside lock of live mm |
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On Sat, Oct 3, 2020 at 11:30 PM Michel Lespinasse <walken@google.com> wrote: > Unrelated to the above: copy_from_user and copy_to_user should not be > called with mmap_lock held; it may be worth adding these assertions > too (probably in separate patches) ?
We already have that: All (hopefully?) the userspace accessors call might_fault(), and that does might_lock_read(¤t->mm->mmap_lock) (if we're not running in a lazytlb kernel thread or KERNEL_DS is on or we're in IRQ context or page faults have explicitly been disabled).
But another place where lockdep asserts should be added is find_vma(); there are currently several architectures that sometimes improperly call that with no lock held:
SPARC's arch_validate_prot(): https://lore.kernel.org/linux-mm/CAG48ez3YsfTfOFKa-Po58e4PNp7FK54MFbkK3aUPSRt3LWtxQA@mail.gmail.com/
nios2 sys_cacheflush(): https://lore.kernel.org/linux-mm/CAG48ez3hxeXU29UGWRH-gRXX2jb5Lc==npbXFt8UDrWO4eHZdQ@mail.gmail.com/
nds32 sys_cacheflush(): https://lore.kernel.org/linux-mm/CAG48ez1UnQEMok9rqFQC4XHBaMmBe=eaedu8Z_RXdjFHTna_LA@mail.gmail.com/
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