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Date: Tue, 10 Aug 2021 11:29:11 +0200 From: Oscar Salvador <osalvador@...e.de> To: Mike Kravetz <mike.kravetz@...cle.com> Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, Muchun Song <songmuchun@...edance.com>, Michal Hocko <mhocko@...e.com>, David Hildenbrand <david@...hat.com>, Matthew Wilcox <willy@...radead.org>, Naoya Horiguchi <naoya.horiguchi@...ux.dev>, Mina Almasry <almasrymina@...gle.com>, Andrew Morton <akpm@...ux-foundation.org> Subject: Re: [PATCH v2 1/3] hugetlb: simplify prep_compound_gigantic_page ref count racing code On 2021-08-09 20:48, Mike Kravetz wrote: > Code in prep_compound_gigantic_page waits for a rcu grace period if it > notices a temporarily inflated ref count on a tail page. This was due > to the identified potential race with speculative page cache references > which could only last for a rcu grace period. This is overly > complicated > as this situation is VERY unlikely to ever happen. Instead, just > quickly > return an error. > Also, only print a warning in prep_compound_gigantic_page instead of > multiple callers. The above makes sense to me. My only question would be: gather_bootmem_prealloc() is an __init function. Can we have speculative refcounts due to e.g: pagecache at that early stage? I think we cannot, but I am not really sure. We might be able to remove that else() in case we cannot have such scenarios. -- Oscar Salvador SUSE L3
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