6971350406
When pagefaults are handled speculatively,the pair of
mmu_notifier_invalidate_range_start/mmu_notifier_invalidate_range_end
calls happen without mmap_lock being taken. This enables the following
race:
mmu_notifier_invalidate_range_start
mmap_write_lock
mmu_notifier_register
mmap_write_unlock
mmu_notifier_invalidate_range_end
In this case mmu_notifier_invalidate_range_end will see a new
subscriber not seen at the time of mmu_notifier_invalidate_range_start
and will call ops->invalidate_range_end for that subscriber without
the matching ops->invalidate_range_start, creating imbalance.
Fix this by introducing a new mm->mmu_notifier_lock percpu_rw_semaphore
to synchronize mmu_notifier_invalidate_range_start/
mmu_notifier_invalidate_range_end with mmu_notifier_register when
handling pagefaults speculatively without holding mmap_lock.
percpu_rw_semaphore is used instead of rw_semaphore to prevent cache
line bouncing in the pagefault path.
Fixes:
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|---|---|---|
| .. | ||
| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
| dt-bindings | ||
| keys | ||
| kunit | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| scsi | ||
| soc | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| vdso | ||
| video | ||
| xen | ||