On 11/14/2013 03:33 PM, Chen Gang wrote: > On 11/14/2013 02:48 PM, Chen Gang wrote: >>> >From the look of it, if an error did occur in init_stub_pte(), >>>> then the special mapping of STUB_CODE and STUB_DATA would not >>>> be installed, so this area would be invisible to munmap and exit, >>>> and with your patch then the pages allocated likely to be leaked. >>>> >> It sounds reasonable to me: "although 'pgd' related with 'mm', but they >> are not installed". But just like you said originally: "better get ACK >> from some mm guys". >> >> >> Hmm... is it another issue: "after STUB_CODE succeeds, but STUB_DATA >> fails, the STUB_CODE will be leaked". >> >> >>>> Which is not to say that the existing code is actually correct: >>>> you're probably right that it's technically wrong. But it would >>>> be very hard to get init_stub_pte() to fail, and has anyone >>>> reported a problem with it? My guess is not, and my own >>>> inclination to dabble here is zero. >>>> >> Yeah. >> > > If we can not get ACK from any mm guys, and we have no enough time > resource to read related source code, for me, I still recommend to > remove p?d_free() in failure processing. > Oh, I am very sorry to Hugh and Richard, I make a mistake in common sense: I recognized incorrect members (I treated Hugh as Richard), Hugh is "mm guys". Next time, I should see the mail carefully, not only for contents, but also for senders. Sorry again to both of you. Thanks. > In the worst cases, we will leak a little memory, and no any other > negative effect, it is an executable way which is no any risks. > > For current mm implementation, it seems we can not assume any thing, > although they sounds (or should be) reasonable (include what you said > about mm). > > > Thanks. > -- Chen Gang -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>