Re: [patch 0/5] lightweight robust futexes: -V1

From: Avi Kivity
Date: Fri Feb 17 2006 - 04:07:16 EST


Daniel Walker wrote:

On Thu, 16 Feb 2006, Ingo Molnar wrote:


that's memory corruption - which robust futexes do not (and cannot)
solve. Robustness is mostly about handling sudden death (e.g. which is
due to oom, or is due to a user killing the task, or due to the
application crashing in some non-memory-corrupting way), but it cannot
handle all possible failure modes.


I don't think this is a weakness in Dave or Inaky's versions. Dave at least maintained the bulk of the information in kernel space. The uaddr was used for the fast locking in userspace, but not for maintaining the robustness .

Correct me if I'm wrong Dave.


In the general case of memory corruption, the data protected by the robust futex might be corrupted, and no robust futex implementation can protect against that, In fact it's a lot more likely since the application code has pointers to the data but not to the robust list.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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