From cb9f753a3731f7fe16447bea45cb6f8e8bb432fb Mon Sep 17 00:00:00 2001
From: Huang Ying <ying.huang@intel.com>
Date: Thu, 5 Apr 2018 16:24:39 -0700
Subject: [PATCH] mm: fix races between swapoff and flush dcache
Thanks to commit 4b3ef9daa4fc ("mm/swap: split swap cache into 64MB
trunks"), after swapoff the address_space associated with the swap
device will be freed. So page_mapping() users which may touch the
address_space need some kind of mechanism to prevent the address_space
from being freed during accessing.
The dcache flushing functions (flush_dcache_page(), etc) in architecture
specific code may access the address_space of swap device for anonymous
pages in swap cache via page_mapping() function. But in some cases
there are no mechanisms to prevent the swap device from being swapoff,
for example,
CPU1 CPU2
__get_user_pages() swapoff()
flush_dcache_page()
mapping = page_mapping()
... exit_swap_address_space()
... kvfree(spaces)
mapping_mapped(mapping)
The address space may be accessed after being freed.
But from cachetlb.txt and Russell King, flush_dcache_page() only care
about file cache pages, for anonymous pages, flush_anon_page() should be
used. The implementation of flush_dcache_page() in all architectures
follows this too. They will check whether page_mapping() is NULL and
whether mapping_mapped() is true to determine whether to flush the
dcache immediately. And they will use interval tree (mapping->i_mmap)
to find all user space mappings. While mapping_mapped() and
mapping->i_mmap isn't used by anonymous pages in swap cache at all.
So, to fix the race between swapoff and flush dcache, __page_mapping()
is add to return the address_space for file cache pages and NULL
otherwise. All page_mapping() invoking in flush dcache functions are
replaced with page_mapping_file().
[akpm@linux-foundation.org: simplify page_mapping_file(), per Mike]
Link: http://lkml.kernel.org/r/20180305083634.15174-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Zankel <chris@zankel.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/arc/mm/cache.c | 2 +-
arch/arm/mm/copypage-v4mc.c | 2 +-
arch/arm/mm/copypage-v6.c | 2 +-
arch/arm/mm/copypage-xscale.c | 2 +-
arch/arm/mm/fault-armv.c | 2 +-
arch/arm/mm/flush.c | 6 +++---
arch/mips/mm/cache.c | 2 +-
arch/nios2/mm/cacheflush.c | 4 ++--
arch/parisc/kernel/cache.c | 5 +++--
arch/sh/mm/cache-sh4.c | 2 +-
arch/sh/mm/cache-sh7705.c | 2 +-
arch/sparc/kernel/smp_64.c | 8 ++++----
arch/sparc/mm/init_64.c | 6 +++---
arch/sparc/mm/tlb.c | 2 +-
arch/unicore32/mm/flush.c | 2 +-
arch/unicore32/mm/mmu.c | 2 +-
arch/xtensa/mm/cache.c | 2 +-
include/linux/mm.h | 1 +
mm/util.c | 10 ++++++++++
19 files changed, 38 insertions(+), 26 deletions(-)
diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index 2072f3451e9c2..9dbe645ee127e 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -833,7 +833,7 @@ void flush_dcache_page(struct page *page)
}
/* don't handle anon pages here */
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!mapping)
return;
diff --git a/arch/arm/mm/copypage-v4mc.c b/arch/arm/mm/copypage-v4mc.c
index 1267e64133b92..0224416cba3c8 100644
--- a/arch/arm/mm/copypage-v4mc.c
+++ b/arch/arm/mm/copypage-v4mc.c
@@ -70,7 +70,7 @@ void v4_mc_copy_user_highpage(struct page *to, struct page *from,
void *kto = kmap_atomic(to);
if (!test_and_set_bit(PG_dcache_clean, &from->flags))
- __flush_dcache_page(page_mapping(from), from);
+ __flush_dcache_page(page_mapping_file(from), from);
raw_spin_lock(&minicache_lock);
diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c
index 70423345da26c..a698e575e3216 100644
--- a/arch/arm/mm/copypage-v6.c
+++ b/arch/arm/mm/copypage-v6.c
@@ -76,7 +76,7 @@ static void v6_copy_user_highpage_aliasing(struct page *to,
unsigned long kfrom, kto;
if (!test_and_set_bit(PG_dcache_clean, &from->flags))
- __flush_dcache_page(page_mapping(from), from);
+ __flush_dcache_page(page_mapping_file(from), from);
/* FIXME: not highmem safe */
discard_old_kernel_data(page_address(to));
diff --git a/arch/arm/mm/copypage-xscale.c b/arch/arm/mm/copypage-xscale.c
index 0fb85025344d9..97972379f4d6a 100644
--- a/arch/arm/mm/copypage-xscale.c
+++ b/arch/arm/mm/copypage-xscale.c
@@ -90,7 +90,7 @@ void xscale_mc_copy_user_highpage(struct page *to, struct page *from,
void *kto = kmap_atomic(to);
if (!test_and_set_bit(PG_dcache_clean, &from->flags))
- __flush_dcache_page(page_mapping(from), from);
+ __flush_dcache_page(page_mapping_file(from), from);
raw_spin_lock(&minicache_lock);
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index d9e0d00a66990..4d75dae5ac962 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -195,7 +195,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
if (page == ZERO_PAGE(0))
return;
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!test_and_set_bit(PG_dcache_clean, &page->flags))
__flush_dcache_page(mapping, page);
if (mapping) {
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index f1e6190aa7eae..58469623b0158 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -285,7 +285,7 @@ void __sync_icache_dcache(pte_t pteval)
page = pfn_to_page(pfn);
if (cache_is_vipt_aliasing())
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
else
mapping = NULL;
@@ -333,7 +333,7 @@ void flush_dcache_page(struct page *page)
return;
}
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!cache_ops_need_broadcast() &&
mapping && !page_mapcount(page))
@@ -363,7 +363,7 @@ void flush_kernel_dcache_page(struct page *page)
if (cache_is_vivt() || cache_is_vipt_aliasing()) {
struct address_space *mapping;
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!mapping || mapping_mapped(mapping)) {
void *addr;
diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 44ac64d518276..0d3c656feba04 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -86,7 +86,7 @@ SYSCALL_DEFINE3(cacheflush, unsigned long, addr, unsigned long, bytes,
void __flush_dcache_page(struct page *page)
{
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping = page_mapping_file(page);
unsigned long addr;
if (mapping && !mapping_mapped(mapping)) {
diff --git a/arch/nios2/mm/cacheflush.c b/arch/nios2/mm/cacheflush.c
index 87bf88ed04c6c..506f6e1c86d55 100644
--- a/arch/nios2/mm/cacheflush.c
+++ b/arch/nios2/mm/cacheflush.c
@@ -180,7 +180,7 @@ void flush_dcache_page(struct page *page)
if (page == ZERO_PAGE(0))
return;
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
/* Flush this page if there are aliases. */
if (mapping && !mapping_mapped(mapping)) {
@@ -215,7 +215,7 @@ void update_mmu_cache(struct vm_area_struct *vma,
if (page == ZERO_PAGE(0))
return;
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!test_and_set_bit(PG_dcache_clean, &page->flags))
__flush_dcache_page(mapping, page);
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index e3b45546d589b..a99da95fc9fde 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -88,7 +88,8 @@ update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
return;
page = pfn_to_page(pfn);
- if (page_mapping(page) && test_bit(PG_dcache_dirty, &page->flags)) {
+ if (page_mapping_file(page) &&
+ test_bit(PG_dcache_dirty, &page->flags)) {
flush_kernel_dcache_page_addr(pfn_va(pfn));
clear_bit(PG_dcache_dirty, &page->flags);
} else if (parisc_requires_coherency())
@@ -304,7 +305,7 @@ __flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr,
void flush_dcache_page(struct page *page)
{
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping = page_mapping_file(page);
struct vm_area_struct *mpnt;
unsigned long offset;
unsigned long addr, old_addr = 0;
diff --git a/arch/sh/mm/cache-sh4.c b/arch/sh/mm/cache-sh4.c
index 58aaa4f33b812..eee911422cf9e 100644
--- a/arch/sh/mm/cache-sh4.c
+++ b/arch/sh/mm/cache-sh4.c
@@ -112,7 +112,7 @@ static void sh4_flush_dcache_page(void *arg)
struct page *page = arg;
unsigned long addr = (unsigned long)page_address(page);
#ifndef CONFIG_SMP
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping = page_mapping_file(page);
if (mapping && !mapping_mapped(mapping))
clear_bit(PG_dcache_clean, &page->flags);
diff --git a/arch/sh/mm/cache-sh7705.c b/arch/sh/mm/cache-sh7705.c
index 6cd2aa395817a..ed25eba806678 100644
--- a/arch/sh/mm/cache-sh7705.c
+++ b/arch/sh/mm/cache-sh7705.c
@@ -136,7 +136,7 @@ static void __flush_dcache_page(unsigned long phys)
static void sh7705_flush_dcache_page(void *arg)
{
struct page *page = arg;
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping = page_mapping_file(page);
if (mapping && !mapping_mapped(mapping))
clear_bit(PG_dcache_clean, &page->flags);
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index c50182cd2f646..d3ea1f3c06a00 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -929,9 +929,9 @@ static inline void __local_flush_dcache_page(struct page *page)
#ifdef DCACHE_ALIASING_POSSIBLE
__flush_dcache_page(page_address(page),
((tlb_type == spitfire) &&
- page_mapping(page) != NULL));
+ page_mapping_file(page) != NULL));
#else
- if (page_mapping(page) != NULL &&
+ if (page_mapping_file(page) != NULL &&
tlb_type == spitfire)
__flush_icache_page(__pa(page_address(page)));
#endif
@@ -958,7 +958,7 @@ void smp_flush_dcache_page_impl(struct page *page, int cpu)
if (tlb_type == spitfire) {
data0 = ((u64)&xcall_flush_dcache_page_spitfire);
- if (page_mapping(page) != NULL)
+ if (page_mapping_file(page) != NULL)
data0 |= ((u64)1 << 32);
} else if (tlb_type == cheetah || tlb_type == cheetah_plus) {
#ifdef DCACHE_ALIASING_POSSIBLE
@@ -994,7 +994,7 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page)
pg_addr = page_address(page);
if (tlb_type == spitfire) {
data0 = ((u64)&xcall_flush_dcache_page_spitfire);
- if (page_mapping(page) != NULL)
+ if (page_mapping_file(page) != NULL)
data0 |= ((u64)1 << 32);
} else if (tlb_type == cheetah || tlb_type == cheetah_plus) {
#ifdef DCACHE_ALIASING_POSSIBLE
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index cb9ebac6663f3..8aeb1aabe76e0 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -206,9 +206,9 @@ inline void flush_dcache_page_impl(struct page *page)
#ifdef DCACHE_ALIASING_POSSIBLE
__flush_dcache_page(page_address(page),
((tlb_type == spitfire) &&
- page_mapping(page) != NULL));
+ page_mapping_file(page) != NULL));
#else
- if (page_mapping(page) != NULL &&
+ if (page_mapping_file(page) != NULL &&
tlb_type == spitfire)
__flush_icache_page(__pa(page_address(page)));
#endif
@@ -490,7 +490,7 @@ void flush_dcache_page(struct page *page)
this_cpu = get_cpu();
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (mapping && !mapping_mapped(mapping)) {
int dirty = test_bit(PG_dcache_dirty, &page->flags);
if (dirty) {
diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
index b5cfab7116514..3d72d2deb13bb 100644
--- a/arch/sparc/mm/tlb.c
+++ b/arch/sparc/mm/tlb.c
@@ -128,7 +128,7 @@ void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
goto no_cache_flush;
/* A real file page? */
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!mapping)
goto no_cache_flush;
diff --git a/arch/unicore32/mm/flush.c b/arch/unicore32/mm/flush.c
index 6d4c096ffa2a8..74f4d636df2d0 100644
--- a/arch/unicore32/mm/flush.c
+++ b/arch/unicore32/mm/flush.c
@@ -83,7 +83,7 @@ void flush_dcache_page(struct page *page)
if (page == ZERO_PAGE(0))
return;
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (mapping && !mapping_mapped(mapping))
clear_bit(PG_dcache_clean, &page->flags);
diff --git a/arch/unicore32/mm/mmu.c b/arch/unicore32/mm/mmu.c
index 4f5a532bee131..0c94b7b4514dc 100644
--- a/arch/unicore32/mm/mmu.c
+++ b/arch/unicore32/mm/mmu.c
@@ -503,7 +503,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
if (page == ZERO_PAGE(0))
return;
- mapping = page_mapping(page);
+ mapping = page_mapping_file(page);
if (!test_and_set_bit(PG_dcache_clean, &page->flags))
__flush_dcache_page(mapping, page);
if (mapping)
diff --git a/arch/xtensa/mm/cache.c b/arch/xtensa/mm/cache.c
index 57dc231a0709d..9220dcde7520c 100644
--- a/arch/xtensa/mm/cache.c
+++ b/arch/xtensa/mm/cache.c
@@ -127,7 +127,7 @@ EXPORT_SYMBOL(copy_user_highpage);
void flush_dcache_page(struct page *page)
{
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping = page_mapping_file(page);
/*
* If we have a mapping but the page is not mapped to user-space
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 40fca1b2b6a17..88d82ba29d724 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1155,6 +1155,7 @@ static inline pgoff_t page_index(struct page *page)
bool page_mapped(struct page *page);
struct address_space *page_mapping(struct page *page);
+struct address_space *page_mapping_file(struct page *page);
/*
* Return true only if the page has been allocated with
diff --git a/mm/util.c b/mm/util.c
index c1250501364fb..029fc2f3b3950 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -515,6 +515,16 @@ struct address_space *page_mapping(struct page *page)
}
EXPORT_SYMBOL(page_mapping);
+/*
+ * For file cache pages, return the address_space, otherwise return NULL
+ */
+struct address_space *page_mapping_file(struct page *page)
+{
+ if (unlikely(PageSwapCache(page)))
+ return NULL;
+ return page_mapping(page);
+}
+
/* Slow path of page_mapcount() for compound pages */
int __page_mapcount(struct page *page)
{
--
GitLab