Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754325AbcLYDAx (ORCPT ); Sat, 24 Dec 2016 22:00:53 -0500 Received: from mail-pg0-f67.google.com ([74.125.83.67]:33013 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752781AbcLYDAu (ORCPT ); Sat, 24 Dec 2016 22:00:50 -0500 From: Nicholas Piggin To: Linus Torvalds Cc: Nicholas Piggin , Dave Hansen , Bob Peterson , Linux Kernel Mailing List , Steven Whitehouse , Andrew Lutomirski , Andreas Gruenbacher , Peter Zijlstra , linux-mm , Mel Gorman Subject: [PATCH 1/2] mm: Use owner_priv bit for PageSwapCache, valid when PageSwapBacked Date: Sun, 25 Dec 2016 13:00:29 +1000 Message-Id: <20161225030030.23219-2-npiggin@gmail.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20161225030030.23219-1-npiggin@gmail.com> References: <20161225030030.23219-1-npiggin@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4791 Lines: 134 A page is not added to the swap cache without being swap backed, so PageSwapBacked mappings can use PG_owner_priv_1 for PageSwapCache. Acked-by: Hugh Dickins Signed-off-by: Nicholas Piggin --- include/linux/page-flags.h | 24 ++++++++++++++++-------- include/trace/events/mmflags.h | 1 - mm/memory-failure.c | 4 +--- mm/migrate.c | 14 ++++++++------ 4 files changed, 25 insertions(+), 18 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 74e4dda91238..a57c909a15e4 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -87,7 +87,6 @@ enum pageflags { PG_private_2, /* If pagecache, has fs aux data */ PG_writeback, /* Page is under writeback */ PG_head, /* A head page */ - PG_swapcache, /* Swap page: swp_entry_t in private */ PG_mappedtodisk, /* Has blocks allocated on-disk */ PG_reclaim, /* To be reclaimed asap */ PG_swapbacked, /* Page is backed by RAM/swap */ @@ -110,6 +109,9 @@ enum pageflags { /* Filesystems */ PG_checked = PG_owner_priv_1, + /* SwapBacked */ + PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ + /* Two page bits are conscripted by FS-Cache to maintain local caching * state. These bits are set on pages belonging to the netfs's inodes * when those inodes are being locally cached. @@ -314,7 +316,13 @@ PAGEFLAG_FALSE(HighMem) #endif #ifdef CONFIG_SWAP -PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) +static __always_inline int PageSwapCache(struct page *page) +{ + return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); + +} +SETPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) +CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) #else PAGEFLAG_FALSE(SwapCache) #endif @@ -701,12 +709,12 @@ static inline void ClearPageSlabPfmemalloc(struct page *page) * Flags checked when a page is freed. Pages being freed should not have * these flags set. It they are, there is a problem. */ -#define PAGE_FLAGS_CHECK_AT_FREE \ - (1UL << PG_lru | 1UL << PG_locked | \ - 1UL << PG_private | 1UL << PG_private_2 | \ - 1UL << PG_writeback | 1UL << PG_reserved | \ - 1UL << PG_slab | 1UL << PG_swapcache | 1UL << PG_active | \ - 1UL << PG_unevictable | __PG_MLOCKED) +#define PAGE_FLAGS_CHECK_AT_FREE \ + (1UL << PG_lru | 1UL << PG_locked | \ + 1UL << PG_private | 1UL << PG_private_2 | \ + 1UL << PG_writeback | 1UL << PG_reserved | \ + 1UL << PG_slab | 1UL << PG_active | \ + 1UL << PG_unevictable | __PG_MLOCKED) /* * Flags checked when a page is prepped for return by the page allocator. diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h index 5a81ab48a2fb..30c2adbdebe8 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -95,7 +95,6 @@ {1UL << PG_private_2, "private_2" }, \ {1UL << PG_writeback, "writeback" }, \ {1UL << PG_head, "head" }, \ - {1UL << PG_swapcache, "swapcache" }, \ {1UL << PG_mappedtodisk, "mappedtodisk" }, \ {1UL << PG_reclaim, "reclaim" }, \ {1UL << PG_swapbacked, "swapbacked" }, \ diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 19e796d36a62..f283c7e0a2a3 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -764,12 +764,11 @@ static int me_huge_page(struct page *p, unsigned long pfn) */ #define dirty (1UL << PG_dirty) -#define sc (1UL << PG_swapcache) +#define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked)) #define unevict (1UL << PG_unevictable) #define mlock (1UL << PG_mlocked) #define writeback (1UL << PG_writeback) #define lru (1UL << PG_lru) -#define swapbacked (1UL << PG_swapbacked) #define head (1UL << PG_head) #define slab (1UL << PG_slab) #define reserved (1UL << PG_reserved) @@ -819,7 +818,6 @@ static struct page_state { #undef mlock #undef writeback #undef lru -#undef swapbacked #undef head #undef slab #undef reserved diff --git a/mm/migrate.c b/mm/migrate.c index 0ed24b1fa77b..87f4d0f81819 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -466,13 +466,15 @@ int migrate_page_move_mapping(struct address_space *mapping, */ newpage->index = page->index; newpage->mapping = page->mapping; - if (PageSwapBacked(page)) - __SetPageSwapBacked(newpage); - get_page(newpage); /* add cache reference */ - if (PageSwapCache(page)) { - SetPageSwapCache(newpage); - set_page_private(newpage, page_private(page)); + if (PageSwapBacked(page)) { + __SetPageSwapBacked(newpage); + if (PageSwapCache(page)) { + SetPageSwapCache(newpage); + set_page_private(newpage, page_private(page)); + } + } else { + VM_BUG_ON_PAGE(PageSwapCache(page), page); } /* Move dirty while page refs frozen and newpage not yet exposed */ -- 2.11.0