Messages in this thread | | | Subject | Re: [RFC PATCH] mm/hugetlb: Avoid soft lockup in set_max_huge_pages() | From | Dave Hansen <> | Date | Tue, 26 Jul 2016 08:58:50 -0700 |
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On 07/26/2016 08:44 AM, Jia He wrote: > This patch is to fix such soft lockup. I thouhgt it is safe to call > cond_resched() because alloc_fresh_gigantic_page and alloc_fresh_huge_page > are out of spin_lock/unlock section.
Yikes. So the call site for both the things you patch is this:
> while (count > persistent_huge_pages(h)) { ... > spin_unlock(&hugetlb_lock); > if (hstate_is_gigantic(h)) > ret = alloc_fresh_gigantic_page(h, nodes_allowed); > else > ret = alloc_fresh_huge_page(h, nodes_allowed); > spin_lock(&hugetlb_lock);
and you choose to patch both of the alloc_*() functions. Why not just fix it at the common call site? Seems like that spin_lock(&hugetlb_lock) could be a cond_resched_lock() which would fix both cases.
Also, putting that cond_resched() inside the for_each_node*() loop is an odd choice. It seems to indicate that the loops can take a long time, which really isn't the case. The _loop_ isn't long, right?
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