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3faa3d9a30
The hfi1 driver registers a mmu_notifier callback when /dev/hfi1_* is opened, and unregisters it when the device is closed. The driver incorrectly assumes that the close will always happen from the same context as the open. In particular, closes due to SIGKILL or OOM killer activity may happen from a different context. In these cases, the wrong mm is passed to mmu_notifier_unregister(), which causes improper reference counting for the victim mm, and eventual memory corruption. Preserve the mm for all open file descriptors and use this mm rather than current->mm for memory operations for the lifetime of that fd. Note: this patch leaves 1 use of current->mm in place. This use is removed in a follow on patch because other functional changes were required prior to that use being removed. If registration fails, there is no reason to keep the handler object around. Free the handler object rather than add it to the list to prevent any mmu_notifier operations, including unregister, when registration fails. Suggested-by: Jim Foraker <foraker1@llnl.gov> Reviewed-by: Dean Luick <dean.luick@intel.com> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com> |
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