Mel Gorman <[email protected]> wrote on 2013/05/15 22:20:35:
> Re: [PATCH] futex: bugfix for futex-key conflict when futex use hugepage > > On Wed, May 15, 2013 at 09:57:03PM +0800, Zhang Yi wrote: > > The futex-keys of processes share futex determined by page-offset, > > mapping-host, and mapping-index of the user space address. User > > appications using hugepage for futex may lead to futex-key conflict. > > > > Assume there are two or more futexes in diffrent normal pages of the > > hugepage, and each futex has the same offset in its normal page, > > causing all the futexes have the same futex-key. > > > > This patch adds the normal page index in the compound page into > > the pgoff of futex-key. > > > > Steps to reproduce the bug: > > 1. The 1st thread map a file of hugetlbfs, and use the return address > > as the 1st mutex's address, and use the return address with PAGE_SIZE > > added as the 2nd mutex's address. > > 2. The 1st thread initialize the two mutexes with pshared attribute, > > and lock the two mutexes. > > 3. The 1st thread create the 2nd thread, and the 2nd thread block on > > the 1st mutex. > > 4. The 1st thread create the 3rd thread, and the 3rd thread block on > > the 2nd mutex. > > 5. The 1st thread unlock the 2nd mutex, the 3rd thread cannot take > > the 2nd mutex, and may block forever. > > > > > > Signed-off-by: Zhang Yi <[email protected]> > > Tested-by: Ma Chenggong <[email protected]> > > Reviewed-by: Thomas Gleixner <[email protected]> > > Reviewed-by: Darren Hart <[email protected]> > > Reviewed-by: Dave Hansen <[email protected]> > > Reviewed-by: Mel Gorman <[email protected]> > > Reviewed-by: Liu Dong <[email protected]> > > Reviewed-by: Cui Yunfeng <[email protected]> > > Reviewed-by: Lu Zhongjun <[email protected]> > > Reviewed-by: Jiang Biao <[email protected]> > > > > Did all these people really review it? I just whinged about the last patch > and didn't put a Reviewed-by on it. That said, I don't actually have a > problem with this patch and I assumed it passed your testing so > I mistakenly think that I should list all the people here. : ) Shall I cleanup the name list and send the patch again? > Reviewed-by: Mel Gorman <[email protected]> > > The others might not agree though. > > I note the conversion from int offset to long offset in futex_key appears > to have gotten lost. Is that in a separate cleanup patch now? In old patch, I add the compound index into offset, so I make the offset from int to long. It is unnecessary for this patch. > > -- > Mel Gorman > SUSE Labs BTW, Does anyone have other advices for the patch? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
