From: Wei Wang <wei.w.wang@intel.com>
To: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org,
akpm@linux-foundation.org
Cc: pbonzini@redhat.com, wei.w.wang@intel.com,
liliang.opensource@gmail.com, yang.zhang.wz@gmail.com,
quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com,
huangzhichao@huawei.com
Subject: [PATCH v28 3/4] mm/page_poison: add a function to expose page poison val to kernel modules
Date: Thu, 8 Feb 2018 17:50:19 +0800 [thread overview]
Message-ID: <1518083420-11108-4-git-send-email-wei.w.wang@intel.com> (raw)
In-Reply-To: <1518083420-11108-1-git-send-email-wei.w.wang@intel.com>
Move the PAGE_POISON value to page_poison.c and add a function to enable
callers from a kernel module to get the poison value if the page poisoning
feature is in use. This also avoids callers directly checking PAGE_POISON
regardless of whether the feature is enabled.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/mm.h | 2 ++
include/linux/poison.h | 7 -------
mm/page_poison.c | 24 ++++++++++++++++++++++++
3 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1c77d88..d95e5d3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2469,11 +2469,13 @@ extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
extern bool page_poisoning_enabled(void);
extern void kernel_poison_pages(struct page *page, int numpages, int enable);
extern bool page_is_poisoned(struct page *page);
+extern bool page_poison_val_get(u8 *val);
#else
static inline bool page_poisoning_enabled(void) { return false; }
static inline void kernel_poison_pages(struct page *page, int numpages,
int enable) { }
static inline bool page_is_poisoned(struct page *page) { return false; }
+static inline bool page_poison_val_get(u8 *val) { return false; };
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
diff --git a/include/linux/poison.h b/include/linux/poison.h
index 15927eb..348bf67 100644
--- a/include/linux/poison.h
+++ b/include/linux/poison.h
@@ -30,13 +30,6 @@
*/
#define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA)
-/********** mm/debug-pagealloc.c **********/
-#ifdef CONFIG_PAGE_POISONING_ZERO
-#define PAGE_POISON 0x00
-#else
-#define PAGE_POISON 0xaa
-#endif
-
/********** mm/page_alloc.c ************/
#define TAIL_MAPPING ((void *) 0x400 + POISON_POINTER_DELTA)
diff --git a/mm/page_poison.c b/mm/page_poison.c
index e83fd44..9a07973 100644
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -7,6 +7,13 @@
#include <linux/poison.h>
#include <linux/ratelimit.h>
+/********** mm/debug-pagealloc.c **********/
+#ifdef CONFIG_PAGE_POISONING_ZERO
+#define PAGE_POISON 0x00
+#else
+#define PAGE_POISON 0xaa
+#endif
+
static bool want_page_poisoning __read_mostly;
static int early_page_poison_param(char *buf)
@@ -30,6 +37,23 @@ bool page_poisoning_enabled(void)
debug_pagealloc_enabled()));
}
+/**
+ * page_poison_val_get - get the page poison value if page poisoning is enabled
+ * @val: the caller's memory to get the page poison value
+ *
+ * Return true with @val stores the poison value if page poisoning is enabled.
+ * Otherwise, return false with @val unchanged.
+ */
+bool page_poison_val_get(u8 *val)
+{
+ if (!page_poisoning_enabled())
+ return false;
+
+ *val = PAGE_POISON;
+ return true;
+}
+EXPORT_SYMBOL_GPL(page_poison_val_get);
+
static void poison_page(struct page *page)
{
void *addr = kmap_atomic(page);
--
2.7.4
next prev parent reply other threads:[~2018-02-08 10:10 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 9:50 [PATCH v28 0/4] Virtio-balloon: support free page reporting Wei Wang
2018-02-08 9:50 ` [PATCH v28 1/4] mm: support reporting free page blocks Wei Wang
2018-02-08 9:50 ` [PATCH v28 2/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT Wei Wang
2018-02-08 9:50 ` Wei Wang [this message]
2018-02-08 19:29 ` [PATCH v28 3/4] mm/page_poison: add a function to expose page poison val to kernel modules Michael S. Tsirkin
2018-02-08 9:50 ` [PATCH v28 4/4] virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON Wei Wang
2018-02-08 19:25 ` Michael S. Tsirkin
2018-02-08 19:31 ` Michael S. Tsirkin
2018-02-08 19:55 ` [PATCH v28 0/4] Virtio-balloon: support free page reporting Michael S. Tsirkin
2018-02-09 3:11 ` Wei Wang
2018-02-09 3:14 ` Michael S. Tsirkin
2018-02-26 4:01 ` Wei Wang
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