From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E639BC54FD0 for ; Mon, 27 Apr 2020 11:12:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B186B2063A for ; Mon, 27 Apr 2020 11:12:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B186B2063A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 62EAF8E0007; Mon, 27 Apr 2020 07:12:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B71A8E0001; Mon, 27 Apr 2020 07:12:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4A5678E0007; Mon, 27 Apr 2020 07:12:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0234.hostedemail.com [216.40.44.234]) by kanga.kvack.org (Postfix) with ESMTP id 2F9388E0001 for ; Mon, 27 Apr 2020 07:12:24 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id E34FA585B for ; Mon, 27 Apr 2020 11:12:23 +0000 (UTC) X-FDA: 76753371366.26.owner94_8940b043ed81f X-HE-Tag: owner94_8940b043ed81f X-Filterd-Recvd-Size: 2551 Received: from huawei.com (szxga06-in.huawei.com [45.249.212.32]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Mon, 27 Apr 2020 11:12:23 +0000 (UTC) Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 23D26B7D0142531E8707; Mon, 27 Apr 2020 19:12:17 +0800 (CST) Received: from host-suse12sp4.huawei.com (10.67.133.23) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.487.0; Mon, 27 Apr 2020 19:12:07 +0800 From: Shijie Hu To: CC: , , , , , , , Subject: [PATCH] [RFC]hugetlbfs: Get unmapped area below TASK_UNMAPPED_BASE for hugetlbfs Date: Mon, 27 Apr 2020 19:10:36 +0800 Message-ID: <20200427111036.74983-1-hushijie3@huawei.com> X-Mailer: git-send-email 2.12.3 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.133.23] X-CFilter-Loop: Reflected 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: In 32-bit programs, the address space is limited. When the normal mmap consumes the space above TASK_UNMAPPED_BASE on legacy mode, it can still successfully obtain unmapped area below TASK_UNMAPPED_BASE, but mmap or shmat for huge pages will fail. This seems "not fair". When the request for huge pages fails, fall back to reuse mmap_min_addr ~ TASK_UNMAPPED_BASE for hugetlbfs. Signed-off-by: Shijie Hu --- fs/hugetlbfs/inode.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index aff8642f0c2e..0f5997394aaa 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -224,7 +224,21 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, info.high_limit = TASK_SIZE; info.align_mask = PAGE_MASK & ~huge_page_mask(h); info.align_offset = 0; - return vm_unmapped_area(&info); + addr = vm_unmapped_area(&info); + + /* + * A failed request for huge pages very likely causes application + * failure, so fall back to the top-down function here. + */ + if (unlikely(offset_in_page(addr))) { + VM_BUG_ON(addr != -ENOMEM); + info.flags = VM_UNMAPPED_AREA_TOPDOWN; + info.low_limit = max(PAGE_SIZE, mmap_min_addr); + info.high_limit = TASK_UNMAPPED_BASE; + addr = vm_unmapped_area(&info); + } + + return addr; } #endif -- 2.12.3