Messages in this thread | | | Subject | Re: [PATCH RFC v2 1/4] mm/mempolicy: Fix get_nodes() mask miscalculation | From | Yisheng Xie <> | Date | Wed, 1 Nov 2017 17:37:36 +0800 |
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Hi Vlastimil,
Thanks for comment! On 2017/10/31 16:34, Vlastimil Babka wrote: > On 10/27/2017 12:14 PM, Yisheng Xie wrote: >> It appears there is a nodemask miscalculation in the get_nodes() >> function in mm/mempolicy.c. This bug has two effects: >> >> 1. It is impossible to specify a length 1 nodemask. >> 2. It is impossible to specify a nodemask containing the last node. > > This should be more specific, which syscalls are you talking about? > I assume it's set_mempolicy() and mbind() and it's the same issue that > was discussed at https://marc.info/?l=linux-mm&m=150732591909576&w=2 ?
I just missed this thread, sorry about that. Not only set_mempolicy() and mbind(), but migrate_pages() also suffers this problem. Maybe related manpage should documented this as your mentioned below.
Thanks Yisheng Xie
> >> Brent have submmit a patch before v2.6.12, however, Andi revert his >> changed for ABI problem. I just resent this patch as RFC, for do not >> clear about what's the problem Andi have met. > > You should have CC'd Andi. As was discussed in the other thread, this > would make existing programs potentially unsafe, so we can't change it. > Instead it should be documented. > >> As manpage of set_mempolicy, If the value of maxnode is zero, the >> nodemask argument is ignored. but we should not ignore the nodemask >> when maxnode is 1. >>
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