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Tue, 23 Feb 2021 19:12:49 -0800 (PST) MIME-Version: 1.0 References: <20210223215544.313871-1-mike.kravetz@oracle.com> In-Reply-To: <20210223215544.313871-1-mike.kravetz@oracle.com> From: Muchun Song Date: Wed, 24 Feb 2021 11:12:12 +0800 Message-ID: Subject: Re: [External] [PATCH] hugetlb: fix uninitialized subpool pointer To: Mike Kravetz Cc: LKML , Linux Memory Management List , Gerald Schaefer , Oscar Salvador , Michal Hocko , Heiko Carstens , Sven Schnelle , Andrew Morton Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 37A9B200038C X-Stat-Signature: jij5xhpjodfo3bp6szc7bqji8zc8dhds Received-SPF: none (bytedance.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-pl1-f174.google.com; client-ip=209.85.214.174 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614136362-508227 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 Wed, Feb 24, 2021 at 5:56 AM Mike Kravetz wrote: > > Gerald Schaefer reported a panic on s390 in hugepage_subpool_put_pages() > with linux-next 5.12.0-20210222. > Call trace: > hugepage_subpool_put_pages.part.0+0x2c/0x138 > __free_huge_page+0xce/0x310 > alloc_pool_huge_page+0x102/0x120 > set_max_huge_pages+0x13e/0x350 > hugetlb_sysctl_handler_common+0xd8/0x110 > hugetlb_sysctl_handler+0x48/0x58 > proc_sys_call_handler+0x138/0x238 > new_sync_write+0x10e/0x198 > vfs_write.part.0+0x12c/0x238 > ksys_write+0x68/0xf8 > do_syscall+0x82/0xd0 > __do_syscall+0xb4/0xc8 > system_call+0x72/0x98 > > This is a result of the change which moved the hugetlb page subpool > pointer from page->private to page[1]->private. When new pages are > allocated from the buddy allocator, the private field of the head > page will be cleared, but the private field of subpages is not modified. > Therefore, old values may remain. > > Fix by initializing hugetlb page subpool pointer in prep_new_huge_page(). > > Fixes: f1280272ae4d ("hugetlb: use page.private for hugetlb specific page flags") > Reported-by: Gerald Schaefer > Signed-off-by: Mike Kravetz Reviewed-by: Muchun Song Thanks. > --- > mm/hugetlb.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index c232cb67dda2..7ae5c18c98a7 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1465,6 +1465,7 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) > { > INIT_LIST_HEAD(&page->lru); > set_compound_page_dtor(page, HUGETLB_PAGE_DTOR); > + hugetlb_set_page_subpool(page, NULL); > set_hugetlb_cgroup(page, NULL); > set_hugetlb_cgroup_rsvd(page, NULL); > spin_lock(&hugetlb_lock); > -- > 2.29.2 >