On Thu 12-12-19 15:52:20, Waiman Long wrote: > On 12/12/19 2:22 PM, Mike Kravetz wrote: > > On 12/12/19 11:04 AM, Davidlohr Bueso wrote: > >> There have been deadlock reports[1, 2] where put_page is called > >> from softirq context and this causes trouble with the hugetlb_lock, > >> as well as potentially the subpool lock. > >> > >> For such an unlikely scenario, lets not add irq dancing overhead > >> to the lock+unlock operations, which could incur in expensive > >> instruction dependencies, particularly when considering hard-irq > >> safety. For example PUSHF+POPF on x86. > >> > >> Instead, just use a workqueue and do the free_huge_page() in regular > >> task context. > >> > >> [1] https://lore.kernel.org/lkml/20191211194615.18502-1-longman@xxxxxxxxxx/ > >> [2] https://lore.kernel.org/lkml/20180905112341.21355-1-aneesh.kumar@xxxxxxxxxxxxx/ > >> > >> Reported-by: Waiman Long <longman@xxxxxxxxxx> > >> Reported-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> > >> Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx> > > Thank you Davidlohr. > > > > The patch does seem fairly simple and straight forward. I need to brush up > > on my workqueue knowledge to provide a full review. > > > > Longman, > > Do you have a test to reproduce the issue? If so, can you try running with > > this patch. > > Yes, I do have a test that can reproduce the issue. I will run it with > the patch and report the status tomorrow. Can you extract guts of the testcase and integrate them into hugetlb test suite? -- Michal Hocko SUSE Labs
