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arc=pass ("microsoft.com:s=arcselector9901:i=1"); spf=pass (imf04.hostedemail.com: domain of jhubbard@nvidia.com designates 40.107.220.82 as permitted sender) smtp.mailfrom=jhubbard@nvidia.com X-Stat-Signature: qr4x8a5yopupg3t8oktiyy39jzb6o911 X-Rspamd-Queue-Id: 6548440003 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1668997922-18624 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 11/18/22 14:20, Sidhartha Kumar wrote: ... > @@ -1950,7 +1949,7 @@ pgoff_t hugetlb_basepage_index(struct page *page) > return (index << compound_order(page_head)) + compound_idx; > } > > -static struct page *alloc_buddy_huge_page(struct hstate *h, > +static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h, > gfp_t gfp_mask, int nid, nodemask_t *nmask, > nodemask_t *node_alloc_noretry) > { > @@ -2009,7 +2008,7 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, > if (node_alloc_noretry && !page && alloc_try_hard) > node_set(nid, *node_alloc_noretry); > > - return page; > + return page_folio(page); 1. This causes a NULL pointer crash when the user requests too many hugetlb pages (you can probably guess how I know this, haha), for example: echo 50000 > /proc/sys/vm/nr_hugepages ...because page_folio() doesn't have a NULL check in there. You will want to do something like this, on top of this current patch: diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 629bb044f063..ffb0f052bbff 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1987,11 +1987,6 @@ static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h, page = NULL; } - if (page) - __count_vm_event(HTLB_BUDDY_PGALLOC); - else - __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); - /* * If we did not specify __GFP_RETRY_MAYFAIL, but still got a page this * indicates an overall state change. Clear bit so that we resume @@ -2008,6 +2003,12 @@ static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h, if (node_alloc_noretry && !page && alloc_try_hard) node_set(nid, *node_alloc_noretry); + if (!page) { + __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); + return NULL; + } + + __count_vm_event(HTLB_BUDDY_PGALLOC); return page_folio(page); } 2. And also, the tests should probably be augmented to run this simple (but easy to overlook) test. 3. And finally, the basic method of replacing page with page_folio(page) is not sufficient, as you can see here. So I'd suggest taking a look through your series to see if you are checking for NULL first, before calling page_folio(page). thanks, -- John Hubbard NVIDIA