mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+)
Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a6e682569e5b..1c423faa4b62 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -864,6 +864,9 @@ static inline void __free_one_page(struct page *page,
buddy_idx = __find_buddy_index(page_idx, order);
buddy = page + (buddy_idx - page_idx);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
--
2.17.1Sorry, please ignore this one.
在 2022/6/17 上午12:17, Xianting Tian 写道:
> Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
> fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
> can be fixed in a similar way too.
>
> In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
> so it would have pfn_base=512 and mem_map began with 512th PFN when
> CONFIG_FLATMEM=y.
> But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
> less than the pfn_base value. We need page_is_buddy() to verify the buddy to
> prevent accessing an invalid buddy.
>
> Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
> Cc: stable@vger.kernel.org
> Reported-by: zjb194813@alibaba-inc.com
> Reported-by: tianhu.hh@alibaba-inc.com
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
> ---
> mm/page_alloc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a6e682569e5b..1c423faa4b62 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -864,6 +864,9 @@ static inline void __free_one_page(struct page *page,
>
> buddy_idx = __find_buddy_index(page_idx, order);
> buddy = page + (buddy_idx - page_idx);
> +
> + if (!page_is_buddy(page, buddy, order))
> + goto done_merging;
> buddy_mt = get_pageblock_migratetype(buddy);
>
> if (migratetype != buddy_mt
On Fri, Jun 17, 2022 at 12:20:19AM +0800, Xianting Tian wrote: > Sorry, please ignore this one. Which "one"? This was a series :(
Sorry for the misleading, I mean just this one in the series, not the whole series, actually this patch is for 4.9, But I forget the add the Label 4.9. So I send the patch for 4.9 again in https://lkml.org/lkml/2022/6/16/782 <https://lkml.org/lkml/2022/6/16/782> 在 2022/6/17 上午12:50, Greg KH 写道: > On Fri, Jun 17, 2022 at 12:20:19AM +0800, Xianting Tian wrote: >> Sorry, please ignore this one. > Which "one"? This was a series :(
Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In unset_migratetype_isolate(), we also need the fix, so move page_is_buddy()
from mm/page_alloc.c to mm/internal.h
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/internal.h | 34 ++++++++++++++++++++++++++++++++++
mm/page_alloc.c | 37 +++----------------------------------
mm/page_isolation.c | 3 ++-
3 files changed, 39 insertions(+), 35 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index cf3cb933eba3..e838d825cfaa 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -340,6 +340,40 @@ static inline bool is_data_mapping(vm_flags_t flags)
return (flags & (VM_WRITE | VM_SHARED | VM_STACK)) == VM_WRITE;
}
+/*
+ * This function checks whether a page is free && is the buddy
+ * we can coalesce a page and its buddy if
+ * (a) the buddy is not in a hole (check before calling!) &&
+ * (b) the buddy is in the buddy system &&
+ * (c) a page and its buddy have the same order &&
+ * (d) a page and its buddy are in the same zone.
+ *
+ * For recording whether a page is in the buddy system, we set PageBuddy.
+ * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
+ *
+ * For recording page's order, we use page_private(page).
+ */
+static inline bool page_is_buddy(struct page *page, struct page *buddy,
+ unsigned int order)
+{
+ if (!page_is_guard(buddy) && !PageBuddy(buddy))
+ return false;
+
+ if (buddy_order(buddy) != order)
+ return false;
+
+ /*
+ * zone check is done late to avoid uselessly calculating
+ * zone/node ids for pages that could never merge.
+ */
+ if (page_zone_id(page) != page_zone_id(buddy))
+ return false;
+
+ VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+ return true;
+}
+
/* mm/util.c */
void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a0b7afae59e9..8a29c0ff1c7b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -875,40 +875,6 @@ static inline void set_buddy_order(struct page *page, unsigned int order)
__SetPageBuddy(page);
}
-/*
- * This function checks whether a page is free && is the buddy
- * we can coalesce a page and its buddy if
- * (a) the buddy is not in a hole (check before calling!) &&
- * (b) the buddy is in the buddy system &&
- * (c) a page and its buddy have the same order &&
- * (d) a page and its buddy are in the same zone.
- *
- * For recording whether a page is in the buddy system, we set PageBuddy.
- * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
- *
- * For recording page's order, we use page_private(page).
- */
-static inline bool page_is_buddy(struct page *page, struct page *buddy,
- unsigned int order)
-{
- if (!page_is_guard(buddy) && !PageBuddy(buddy))
- return false;
-
- if (buddy_order(buddy) != order)
- return false;
-
- /*
- * zone check is done late to avoid uselessly calculating
- * zone/node ids for pages that could never merge.
- */
- if (page_zone_id(page) != page_zone_id(buddy))
- return false;
-
- VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
-
- return true;
-}
-
#ifdef CONFIG_COMPACTION
static inline struct capture_control *task_capc(struct zone *zone)
{
@@ -1118,6 +1084,9 @@ static inline void __free_one_page(struct page *page,
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index a95c2c6562d0..70c1870e786b 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -93,7 +93,8 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
- if (!is_migrate_isolate_page(buddy)) {
+ if (page_is_buddy(page, buddy, order) &&
+ !is_migrate_isolate_page(buddy)) {
__isolate_free_page(page, order);
isolated_page = true;
}
--
2.17.1On Fri, Jun 17, 2022 at 12:17:45AM +0800, Xianting Tian wrote:
> Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
> fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
> can be fixed in a similar way too.
>
> In unset_migratetype_isolate(), we also need the fix, so move page_is_buddy()
> from mm/page_alloc.c to mm/internal.h
>
> In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
> so it would have pfn_base=512 and mem_map began with 512th PFN when
> CONFIG_FLATMEM=y.
> But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
> less than the pfn_base value. We need page_is_buddy() to verify the buddy to
> prevent accessing an invalid buddy.
>
> Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
> Cc: stable@vger.kernel.org
> Reported-by: zjb194813@alibaba-inc.com
> Reported-by: tianhu.hh@alibaba-inc.com
> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
> ---
> mm/internal.h | 34 ++++++++++++++++++++++++++++++++++
> mm/page_alloc.c | 37 +++----------------------------------
> mm/page_isolation.c | 3 ++-
> 3 files changed, 39 insertions(+), 35 deletions(-)
What is the commit id of this in Linus's tree?
thanks,
greg k-h
在 2022/6/20 下午6:17, Greg KH 写道:
> On Fri, Jun 17, 2022 at 12:17:45AM +0800, Xianting Tian wrote:
>> Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
>> fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
>> can be fixed in a similar way too.
>>
>> In unset_migratetype_isolate(), we also need the fix, so move page_is_buddy()
>> from mm/page_alloc.c to mm/internal.h
>>
>> In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
>> so it would have pfn_base=512 and mem_map began with 512th PFN when
>> CONFIG_FLATMEM=y.
>> But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
>> less than the pfn_base value. We need page_is_buddy() to verify the buddy to
>> prevent accessing an invalid buddy.
>>
>> Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
>> Cc: stable@vger.kernel.org
>> Reported-by: zjb194813@alibaba-inc.com
>> Reported-by: tianhu.hh@alibaba-inc.com
>> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>> ---
>> mm/internal.h | 34 ++++++++++++++++++++++++++++++++++
>> mm/page_alloc.c | 37 +++----------------------------------
>> mm/page_isolation.c | 3 ++-
>> 3 files changed, 39 insertions(+), 35 deletions(-)
> What is the commit id of this in Linus's tree?
It is also this one，
commit 787af64d05cd528aac9ad16752d11bb1c6061bb9
Author: Zi Yan <ziy@nvidia.com>
Date: Wed Mar 30 15:45:43 2022 -0700
mm: page_alloc: validate buddy before check its migratetype.
Whenever a buddy page is found, page_is_buddy() should be called to
check its validity. Add the missing check during pageblock merge
check.
Fixes: 1dd214b8f21c ("mm: page_alloc: avoid merging
non-fallbackable pageblocks with others")
Link:
https://lore.kernel.org/all/20220330154208.71aca532@gandalf.local.home/
Reported-and-tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
>
> thanks,
>
> greg k-h
On Mon, Jun 20, 2022 at 06:54:44PM +0800, Xianting Tian wrote:
>
> 在 2022/6/20 下午6:17, Greg KH 写道:
> > On Fri, Jun 17, 2022 at 12:17:45AM +0800, Xianting Tian wrote:
> > > Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
> > > fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
> > > can be fixed in a similar way too.
> > >
> > > In unset_migratetype_isolate(), we also need the fix, so move page_is_buddy()
> > > from mm/page_alloc.c to mm/internal.h
> > >
> > > In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
> > > so it would have pfn_base=512 and mem_map began with 512th PFN when
> > > CONFIG_FLATMEM=y.
> > > But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
> > > less than the pfn_base value. We need page_is_buddy() to verify the buddy to
> > > prevent accessing an invalid buddy.
> > >
> > > Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
> > > Cc: stable@vger.kernel.org
> > > Reported-by: zjb194813@alibaba-inc.com
> > > Reported-by: tianhu.hh@alibaba-inc.com
> > > Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
> > > ---
> > > mm/internal.h | 34 ++++++++++++++++++++++++++++++++++
> > > mm/page_alloc.c | 37 +++----------------------------------
> > > mm/page_isolation.c | 3 ++-
> > > 3 files changed, 39 insertions(+), 35 deletions(-)
> > What is the commit id of this in Linus's tree?
>
> It is also this one，
>
> commit 787af64d05cd528aac9ad16752d11bb1c6061bb9
> Author: Zi Yan <ziy@nvidia.com>
> Date: Wed Mar 30 15:45:43 2022 -0700
>
> mm: page_alloc: validate buddy before check its migratetype.
>
> Whenever a buddy page is found, page_is_buddy() should be called to
> check its validity. Add the missing check during pageblock merge check.
>
> Fixes: 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable
> pageblocks with others")
> Link:
> https://lore.kernel.org/all/20220330154208.71aca532@gandalf.local.home/
> Reported-and-tested-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit looks nothing like what you posted here.
Why the vast difference with no explaination as to why these are so
different from the other backports you provided here? Also why is the
subject lines changed?
Something went really wrong here, I'm going to drop all of these from
the stable queues and wait for a full series of all new backports, with
the correct upstream commit id added, and the original signed-off-by
lines preserved.
thanks,
greg k-h
Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bfbccc739332..6e994a2013aa 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -866,6 +866,9 @@ static inline void __free_one_page(struct page *page,
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
--
2.17.1Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f08ce248af2a..8f56e6a193cc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -959,6 +959,9 @@ static inline void __free_one_page(struct page *page,
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
--
2.17.1Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In unset_migratetype_isolate(), we also need the fix, so move page_is_buddy()
from mm/page_alloc.c to mm/internal.h
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/internal.h | 34 ++++++++++++++++++++++++++++++++++
mm/page_alloc.c | 37 +++----------------------------------
mm/page_isolation.c | 3 ++-
3 files changed, 39 insertions(+), 35 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index d80300392a19..dfa80bdfe5c6 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -386,6 +386,40 @@ static inline bool is_data_mapping(vm_flags_t flags)
return (flags & (VM_WRITE | VM_SHARED | VM_STACK)) == VM_WRITE;
}
+/*
+ * This function checks whether a page is free && is the buddy
+ * we can coalesce a page and its buddy if
+ * (a) the buddy is not in a hole (check before calling!) &&
+ * (b) the buddy is in the buddy system &&
+ * (c) a page and its buddy have the same order &&
+ * (d) a page and its buddy are in the same zone.
+ *
+ * For recording whether a page is in the buddy system, we set PageBuddy.
+ * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
+ *
+ * For recording page's order, we use page_private(page).
+ */
+static inline bool page_is_buddy(struct page *page, struct page *buddy,
+ unsigned int order)
+{
+ if (!page_is_guard(buddy) && !PageBuddy(buddy))
+ return false;
+
+ if (buddy_order(buddy) != order)
+ return false;
+
+ /*
+ * zone check is done late to avoid uselessly calculating
+ * zone/node ids for pages that could never merge.
+ */
+ if (page_zone_id(page) != page_zone_id(buddy))
+ return false;
+
+ VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+
+ return true;
+}
+
/* mm/util.c */
void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
struct vm_area_struct *prev);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b1caa1c6c887..78ada8dedefb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -886,40 +886,6 @@ static inline void set_buddy_order(struct page *page, unsigned int order)
__SetPageBuddy(page);
}
-/*
- * This function checks whether a page is free && is the buddy
- * we can coalesce a page and its buddy if
- * (a) the buddy is not in a hole (check before calling!) &&
- * (b) the buddy is in the buddy system &&
- * (c) a page and its buddy have the same order &&
- * (d) a page and its buddy are in the same zone.
- *
- * For recording whether a page is in the buddy system, we set PageBuddy.
- * Setting, clearing, and testing PageBuddy is serialized by zone->lock.
- *
- * For recording page's order, we use page_private(page).
- */
-static inline bool page_is_buddy(struct page *page, struct page *buddy,
- unsigned int order)
-{
- if (!page_is_guard(buddy) && !PageBuddy(buddy))
- return false;
-
- if (buddy_order(buddy) != order)
- return false;
-
- /*
- * zone check is done late to avoid uselessly calculating
- * zone/node ids for pages that could never merge.
- */
- if (page_zone_id(page) != page_zone_id(buddy))
- return false;
-
- VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
-
- return true;
-}
-
#ifdef CONFIG_COMPACTION
static inline struct capture_control *task_capc(struct zone *zone)
{
@@ -1129,6 +1095,9 @@ static inline void __free_one_page(struct page *page,
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f67c4c70f17f..5d14cef812ee 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -93,7 +93,8 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
- if (!is_migrate_isolate_page(buddy)) {
+ if (page_is_buddy(page, buddy, order) &&
+ !is_migrate_isolate_page(buddy)) {
isolated_page = !!__isolate_free_page(page, order);
/*
* Isolating a free page in an isolated pageblock
--
2.17.1Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9c35403d9646..8fc7f1803976 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -858,6 +858,9 @@ static inline void __free_one_page(struct page *page,
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
--
2.17.1Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
can be fixed in a similar way too.
In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
so it would have pfn_base=512 and mem_map began with 512th PFN when
CONFIG_FLATMEM=y.
But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
less than the pfn_base value. We need page_is_buddy() to verify the buddy to
prevent accessing an invalid buddy.
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Cc: stable@vger.kernel.org
Reported-by: zjb194813@alibaba-inc.com
Reported-by: tianhu.hh@alibaba-inc.com
Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f3418edb136b..2d845ddfabad 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1049,6 +1049,9 @@ static inline void __free_one_page(struct page *page,
buddy_pfn = __find_buddy_pfn(pfn, order);
buddy = page + (buddy_pfn - pfn);
+
+ if (!page_is_buddy(page, buddy, order))
+ goto done_merging;
buddy_mt = get_pageblock_migratetype(buddy);
if (migratetype != buddy_mt
--
2.17.1© 2016 - 2026 Red Hat, Inc.