From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753006AbeCEQag (ORCPT ); Mon, 5 Mar 2018 11:30:36 -0500 Received: from mga04.intel.com ([192.55.52.120]:44459 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752401AbeCEQ01 (ORCPT ); Mon, 5 Mar 2018 11:26:27 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,427,1515484800"; d="scan'208";a="23065199" From: "Kirill A. Shutemov" To: Ingo Molnar , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" , Tom Lendacky Cc: Dave Hansen , Kai Huang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" Subject: [RFC, PATCH 13/22] mm, rmap: Free encrypted pages once mapcount drops to zero Date: Mon, 5 Mar 2018 19:26:01 +0300 Message-Id: <20180305162610.37510-14-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180305162610.37510-1-kirill.shutemov@linux.intel.com> References: <20180305162610.37510-1-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Freeing encrypted pages may require special treatment such as flush cache to avoid aliasing. Anonymous pages cannot be mapped back once the last mapcount is gone. That's a good place to add hook to free encrypted page. At later point we may not have valid anon_vma around to get KeyID. Signed-off-by: Kirill A. Shutemov --- include/linux/mm.h | 1 + mm/rmap.c | 34 ++++++++++++++++++++++++++++++++-- 2 files changed, 33 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 7a4285f09c99..7ab5e39e3195 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1981,6 +1981,7 @@ extern void mem_init_print_info(const char *str); extern void reserve_bootmem_region(phys_addr_t start, phys_addr_t end); extern void prep_encrypt_page(struct page *page, gfp_t gfp, unsigned int order); +extern void free_encrypt_page(struct page *page, int keyid, unsigned int order); /* Free the reserved page into the buddy system, so it gets managed. */ static inline void __free_reserved_page(struct page *page) diff --git a/mm/rmap.c b/mm/rmap.c index c0470a69a4c9..4bff992fc106 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -81,6 +81,21 @@ static inline void arch_anon_vma_init(struct anon_vma *anon_vma, } #endif +#ifndef anon_vma_encrypted +static inline bool anon_vma_encrypted(struct anon_vma *anon_vma) +{ + return false; +} +#endif + +#ifndef anon_vma_keyid +static inline int anon_vma_keyid(struct anon_vma *anon_vma) +{ + BUILD_BUG(); + return 0; +} +#endif + static inline struct anon_vma *anon_vma_alloc(struct vm_area_struct *vma) { struct anon_vma *anon_vma; @@ -1258,6 +1273,7 @@ static void page_remove_file_rmap(struct page *page, bool compound) static void page_remove_anon_compound_rmap(struct page *page) { + struct anon_vma *anon_vma; int i, nr; if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) @@ -1292,6 +1308,12 @@ static void page_remove_anon_compound_rmap(struct page *page) __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr); deferred_split_huge_page(page); } + + anon_vma = page_anon_vma(page); + if (anon_vma_encrypted(anon_vma)) { + int keyid = anon_vma_keyid(anon_vma); + free_encrypt_page(page, keyid, compound_order(page)); + } } /** @@ -1303,6 +1325,9 @@ static void page_remove_anon_compound_rmap(struct page *page) */ void page_remove_rmap(struct page *page, bool compound) { + struct page *head; + struct anon_vma *anon_vma; + if (!PageAnon(page)) return page_remove_file_rmap(page, compound); @@ -1323,8 +1348,13 @@ void page_remove_rmap(struct page *page, bool compound) if (unlikely(PageMlocked(page))) clear_page_mlock(page); - if (PageTransCompound(page)) - deferred_split_huge_page(compound_head(page)); + head = compound_head(page); + if (PageTransHuge(head)) + deferred_split_huge_page(head); + + anon_vma = page_anon_vma(head); + if (anon_vma_encrypted(anon_vma)) + free_encrypt_page(page, anon_vma_keyid(anon_vma), 0); /* * It would be tidy to reset the PageAnon mapping here, -- 2.16.1