From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 511B82E40E; Fri, 24 Nov 2023 18:41:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RYsQk/sE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BD39C433C8; Fri, 24 Nov 2023 18:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700851284; bh=ikGz/aeY+IRGmZzQwcd/7R0nyIhcfQcYObb61L42OEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RYsQk/sEJ3NVTjtvhuqZyGEIGysrmEjk486aAreMP7ptygqRgsfX0qvkgayLLHj13 yiWOl2hCwuOFjqGX9Gi9xKxJyDOhqv2Gs4Tc6yFgdZqruBENqlnwPcRU5Yv0wuDZIU jXnx7G89xEJ/jq//ZSf1aiusnR1qKVwc7qYIcke4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peter Xu , Mike Kravetz , David Hildenbrand , Andrea Arcangeli , Hugh Dickins , James Houghton , Jason Gunthorpe , John Hubbard , "Kirill A . Shutemov" , Lorenzo Stoakes , Matthew Wilcox , "Mike Rapoport (IBM)" , Vlastimil Babka , Yang Shi , Andrew Morton , Sasha Levin Subject: [PATCH 6.5 379/491] mm/hugetlb: prepare hugetlb_follow_page_mask() for FOLL_PIN Date: Fri, 24 Nov 2023 17:50:15 +0000 Message-ID: <20231124172035.979372545@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124172024.664207345@linuxfoundation.org> References: <20231124172024.664207345@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Xu [ Upstream commit 458568c92953dee3716234711f1a2830a35261f3 ] follow_page() doesn't use FOLL_PIN, meanwhile hugetlb seems to not be the target of FOLL_WRITE either. However add the checks. Namely, either the need to CoW due to missing write bit, or proper unsharing on !AnonExclusive pages over R/O pins to reject the follow page. That brings this function closer to follow_hugetlb_page(). So we don't care before, and also for now. But we'll care if we switch over slow-gup to use hugetlb_follow_page_mask(). We'll also care when to return -EMLINK properly, as that's the gup internal api to mean "we should unshare". Not really needed for follow page path, though. When at it, switching the try_grab_page() to use WARN_ON_ONCE(), to be clear that it just should never fail. When error happens, instead of setting page==NULL, capture the errno instead. Link: https://lkml.kernel.org/r/20230628215310.73782-3-peterx@redhat.com Signed-off-by: Peter Xu Reviewed-by: Mike Kravetz Reviewed-by: David Hildenbrand Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: James Houghton Cc: Jason Gunthorpe Cc: John Hubbard Cc: Kirill A . Shutemov Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Mike Rapoport (IBM) Cc: Vlastimil Babka Cc: Yang Shi Signed-off-by: Andrew Morton Stable-dep-of: 426056efe835 ("mm/hugetlb: use nth_page() in place of direct struct page manipulation") Signed-off-by: Sasha Levin --- mm/hugetlb.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 097b81c37597e..d231f23088a77 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6521,13 +6521,7 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, struct page *page = NULL; spinlock_t *ptl; pte_t *pte, entry; - - /* - * FOLL_PIN is not supported for follow_page(). Ordinary GUP goes via - * follow_hugetlb_page(). - */ - if (WARN_ON_ONCE(flags & FOLL_PIN)) - return NULL; + int ret; hugetlb_vma_lock_read(vma); pte = hugetlb_walk(vma, haddr, huge_page_size(h)); @@ -6537,8 +6531,23 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, ptl = huge_pte_lock(h, mm, pte); entry = huge_ptep_get(pte); if (pte_present(entry)) { - page = pte_page(entry) + - ((address & ~huge_page_mask(h)) >> PAGE_SHIFT); + page = pte_page(entry); + + if (!huge_pte_write(entry)) { + if (flags & FOLL_WRITE) { + page = NULL; + goto out; + } + + if (gup_must_unshare(vma, flags, page)) { + /* Tell the caller to do unsharing */ + page = ERR_PTR(-EMLINK); + goto out; + } + } + + page += ((address & ~huge_page_mask(h)) >> PAGE_SHIFT); + /* * Note that page may be a sub-page, and with vmemmap * optimizations the page struct may be read only. @@ -6548,8 +6557,10 @@ struct page *hugetlb_follow_page_mask(struct vm_area_struct *vma, * try_grab_page() should always be able to get the page here, * because we hold the ptl lock and have verified pte_present(). */ - if (try_grab_page(page, flags)) { - page = NULL; + ret = try_grab_page(page, flags); + + if (WARN_ON_ONCE(ret)) { + page = ERR_PTR(ret); goto out; } } -- 2.42.0