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. -Longman
