<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/mm, branch v6.6.37</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>mm/page_alloc: Separate THP PCP into movable and non-movable categories</title>
<updated>2024-07-05T07:34:05+00:00</updated>
<author>
<name>yangge</name>
<email>yangge1116@126.com</email>
</author>
<published>2024-06-20T00:59:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c5978b996260534aca5ff1b6dcbef92c2bbea947'/>
<id>c5978b996260534aca5ff1b6dcbef92c2bbea947</id>
<content type='text'>
commit bf14ed81f571f8dba31cd72ab2e50fbcc877cc31 upstream.

Since commit 5d0a661d808f ("mm/page_alloc: use only one PCP list for
THP-sized allocations") no longer differentiates the migration type of
pages in THP-sized PCP list, it's possible that non-movable allocation
requests may get a CMA page from the list, in some cases, it's not
acceptable.

If a large number of CMA memory are configured in system (for example, the
CMA memory accounts for 50% of the system memory), starting a virtual
machine with device passthrough will get stuck.  During starting the
virtual machine, it will call pin_user_pages_remote(..., FOLL_LONGTERM,
...) to pin memory.  Normally if a page is present and in CMA area,
pin_user_pages_remote() will migrate the page from CMA area to non-CMA
area because of FOLL_LONGTERM flag.  But if non-movable allocation
requests return CMA memory, migrate_longterm_unpinnable_pages() will
migrate a CMA page to another CMA page, which will fail to pass the check
in check_and_migrate_movable_pages() and cause migration endless.

Call trace:
pin_user_pages_remote
--__gup_longterm_locked // endless loops in this function
----_get_user_pages_locked
----check_and_migrate_movable_pages
------migrate_longterm_unpinnable_pages
--------alloc_migration_target

This problem will also have a negative impact on CMA itself.  For example,
when CMA is borrowed by THP, and we need to reclaim it through cma_alloc()
or dma_alloc_coherent(), we must move those pages out to ensure CMA's
users can retrieve that contigous memory.  Currently, CMA's memory is
occupied by non-movable pages, meaning we can't relocate them.  As a
result, cma_alloc() is more likely to fail.

To fix the problem above, we add one PCP list for THP, which will not
introduce a new cacheline for struct per_cpu_pages.  THP will have 2 PCP
lists, one PCP list is used by MOVABLE allocation, and the other PCP list
is used by UNMOVABLE allocation.  MOVABLE allocation contains GPF_MOVABLE,
and UNMOVABLE allocation contains GFP_UNMOVABLE and GFP_RECLAIMABLE.

Link: https://lkml.kernel.org/r/1718845190-4456-1-git-send-email-yangge1116@126.com
Fixes: 5d0a661d808f ("mm/page_alloc: use only one PCP list for THP-sized allocations")
Signed-off-by: yangge &lt;yangge1116@126.com&gt;
Cc: Baolin Wang &lt;baolin.wang@linux.alibaba.com&gt;
Cc: Barry Song &lt;21cnbao@gmail.com&gt;
Cc: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit bf14ed81f571f8dba31cd72ab2e50fbcc877cc31 upstream.

Since commit 5d0a661d808f ("mm/page_alloc: use only one PCP list for
THP-sized allocations") no longer differentiates the migration type of
pages in THP-sized PCP list, it's possible that non-movable allocation
requests may get a CMA page from the list, in some cases, it's not
acceptable.

If a large number of CMA memory are configured in system (for example, the
CMA memory accounts for 50% of the system memory), starting a virtual
machine with device passthrough will get stuck.  During starting the
virtual machine, it will call pin_user_pages_remote(..., FOLL_LONGTERM,
...) to pin memory.  Normally if a page is present and in CMA area,
pin_user_pages_remote() will migrate the page from CMA area to non-CMA
area because of FOLL_LONGTERM flag.  But if non-movable allocation
requests return CMA memory, migrate_longterm_unpinnable_pages() will
migrate a CMA page to another CMA page, which will fail to pass the check
in check_and_migrate_movable_pages() and cause migration endless.

Call trace:
pin_user_pages_remote
--__gup_longterm_locked // endless loops in this function
----_get_user_pages_locked
----check_and_migrate_movable_pages
------migrate_longterm_unpinnable_pages
--------alloc_migration_target

This problem will also have a negative impact on CMA itself.  For example,
when CMA is borrowed by THP, and we need to reclaim it through cma_alloc()
or dma_alloc_coherent(), we must move those pages out to ensure CMA's
users can retrieve that contigous memory.  Currently, CMA's memory is
occupied by non-movable pages, meaning we can't relocate them.  As a
result, cma_alloc() is more likely to fail.

To fix the problem above, we add one PCP list for THP, which will not
introduce a new cacheline for struct per_cpu_pages.  THP will have 2 PCP
lists, one PCP list is used by MOVABLE allocation, and the other PCP list
is used by UNMOVABLE allocation.  MOVABLE allocation contains GPF_MOVABLE,
and UNMOVABLE allocation contains GFP_UNMOVABLE and GFP_RECLAIMABLE.

Link: https://lkml.kernel.org/r/1718845190-4456-1-git-send-email-yangge1116@126.com
Fixes: 5d0a661d808f ("mm/page_alloc: use only one PCP list for THP-sized allocations")
Signed-off-by: yangge &lt;yangge1116@126.com&gt;
Cc: Baolin Wang &lt;baolin.wang@linux.alibaba.com&gt;
Cc: Barry Song &lt;21cnbao@gmail.com&gt;
Cc: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: fix incorrect vbq reference in purge_fragmented_block</title>
<updated>2024-07-05T07:33:55+00:00</updated>
<author>
<name>Zhaoyang Huang</name>
<email>zhaoyang.huang@unisoc.com</email>
</author>
<published>2024-06-07T02:31:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=88e0ad40d08a73a74c597e69f4cd2d1fba3838b5'/>
<id>88e0ad40d08a73a74c597e69f4cd2d1fba3838b5</id>
<content type='text'>
commit 8c61291fd8500e3b35c7ec0c781b273d8cc96cde upstream.

xa_for_each() in _vm_unmap_aliases() loops through all vbs.  However,
since commit 062eacf57ad9 ("mm: vmalloc: remove a global vmap_blocks
xarray") the vb from xarray may not be on the corresponding CPU
vmap_block_queue.  Consequently, purge_fragmented_block() might use the
wrong vbq-&gt;lock to protect the free list, leading to vbq-&gt;free breakage.

Incorrect lock protection can exhaust all vmalloc space as follows:
CPU0                                            CPU1
+--------------------------------------------+
|    +--------------------+     +-----+      |
+--&gt; |                    |----&gt;|     |------+
     | CPU1:vbq free_list |     | vb1 |
+--- |                    |&lt;----|     |&lt;-----+
|    +--------------------+     +-----+      |
+--------------------------------------------+

_vm_unmap_aliases()                             vb_alloc()
                                                new_vmap_block()
xa_for_each(&amp;vbq-&gt;vmap_blocks, idx, vb)
--&gt; vb in CPU1:vbq-&gt;freelist

purge_fragmented_block(vb)
spin_lock(&amp;vbq-&gt;lock)                           spin_lock(&amp;vbq-&gt;lock)
--&gt; use CPU0:vbq-&gt;lock                          --&gt; use CPU1:vbq-&gt;lock

list_del_rcu(&amp;vb-&gt;free_list)                    list_add_tail_rcu(&amp;vb-&gt;free_list, &amp;vbq-&gt;free)
    __list_del(vb-&gt;prev, vb-&gt;next)
        next-&gt;prev = prev
    +--------------------+
    |                    |
    | CPU1:vbq free_list |
+---|                    |&lt;--+
|   +--------------------+   |
+----------------------------+
                                                __list_add(new, head-&gt;prev, head)
+--------------------------------------------+
|    +--------------------+     +-----+      |
+--&gt; |                    |----&gt;|     |------+
     | CPU1:vbq free_list |     | vb2 |
+--- |                    |&lt;----|     |&lt;-----+
|    +--------------------+     +-----+      |
+--------------------------------------------+

        prev-&gt;next = next
+--------------------------------------------+
|----------------------------+               |
|    +--------------------+  |  +-----+      |
+--&gt; |                    |--+  |     |------+
     | CPU1:vbq free_list |     | vb2 |
+--- |                    |&lt;----|     |&lt;-----+
|    +--------------------+     +-----+      |
+--------------------------------------------+
Here’s a list breakdown. All vbs, which were to be added to
‘prev’, cannot be used by list_for_each_entry_rcu(vb, &amp;vbq-&gt;free,
free_list) in vb_alloc(). Thus, vmalloc space is exhausted.

This issue affects both erofs and f2fs, the stacktrace is as follows:
erofs:
[&lt;ffffffd4ffb93ad4&gt;] __switch_to+0x174
[&lt;ffffffd4ffb942f0&gt;] __schedule+0x624
[&lt;ffffffd4ffb946f4&gt;] schedule+0x7c
[&lt;ffffffd4ffb947cc&gt;] schedule_preempt_disabled+0x24
[&lt;ffffffd4ffb962ec&gt;] __mutex_lock+0x374
[&lt;ffffffd4ffb95998&gt;] __mutex_lock_slowpath+0x14
[&lt;ffffffd4ffb95954&gt;] mutex_lock+0x24
[&lt;ffffffd4fef2900c&gt;] reclaim_and_purge_vmap_areas+0x44
[&lt;ffffffd4fef25908&gt;] alloc_vmap_area+0x2e0
[&lt;ffffffd4fef24ea0&gt;] vm_map_ram+0x1b0
[&lt;ffffffd4ff1b46f4&gt;] z_erofs_lz4_decompress+0x278
[&lt;ffffffd4ff1b8ac4&gt;] z_erofs_decompress_queue+0x650
[&lt;ffffffd4ff1b8328&gt;] z_erofs_runqueue+0x7f4
[&lt;ffffffd4ff1b66a8&gt;] z_erofs_read_folio+0x104
[&lt;ffffffd4feeb6fec&gt;] filemap_read_folio+0x6c
[&lt;ffffffd4feeb68c4&gt;] filemap_fault+0x300
[&lt;ffffffd4fef0ecac&gt;] __do_fault+0xc8
[&lt;ffffffd4fef0c908&gt;] handle_mm_fault+0xb38
[&lt;ffffffd4ffb9f008&gt;] do_page_fault+0x288
[&lt;ffffffd4ffb9ed64&gt;] do_translation_fault[jt]+0x40
[&lt;ffffffd4fec39c78&gt;] do_mem_abort+0x58
[&lt;ffffffd4ffb8c3e4&gt;] el0_ia+0x70
[&lt;ffffffd4ffb8c260&gt;] el0t_64_sync_handler[jt]+0xb0
[&lt;ffffffd4fec11588&gt;] ret_to_user[jt]+0x0

f2fs:
[&lt;ffffffd4ffb93ad4&gt;] __switch_to+0x174
[&lt;ffffffd4ffb942f0&gt;] __schedule+0x624
[&lt;ffffffd4ffb946f4&gt;] schedule+0x7c
[&lt;ffffffd4ffb947cc&gt;] schedule_preempt_disabled+0x24
[&lt;ffffffd4ffb962ec&gt;] __mutex_lock+0x374
[&lt;ffffffd4ffb95998&gt;] __mutex_lock_slowpath+0x14
[&lt;ffffffd4ffb95954&gt;] mutex_lock+0x24
[&lt;ffffffd4fef2900c&gt;] reclaim_and_purge_vmap_areas+0x44
[&lt;ffffffd4fef25908&gt;] alloc_vmap_area+0x2e0
[&lt;ffffffd4fef24ea0&gt;] vm_map_ram+0x1b0
[&lt;ffffffd4ff1a3b60&gt;] f2fs_prepare_decomp_mem+0x144
[&lt;ffffffd4ff1a6c24&gt;] f2fs_alloc_dic+0x264
[&lt;ffffffd4ff175468&gt;] f2fs_read_multi_pages+0x428
[&lt;ffffffd4ff17b46c&gt;] f2fs_mpage_readpages+0x314
[&lt;ffffffd4ff1785c4&gt;] f2fs_readahead+0x50
[&lt;ffffffd4feec3384&gt;] read_pages+0x80
[&lt;ffffffd4feec32c0&gt;] page_cache_ra_unbounded+0x1a0
[&lt;ffffffd4feec39e8&gt;] page_cache_ra_order+0x274
[&lt;ffffffd4feeb6cec&gt;] do_sync_mmap_readahead+0x11c
[&lt;ffffffd4feeb6764&gt;] filemap_fault+0x1a0
[&lt;ffffffd4ff1423bc&gt;] f2fs_filemap_fault+0x28
[&lt;ffffffd4fef0ecac&gt;] __do_fault+0xc8
[&lt;ffffffd4fef0c908&gt;] handle_mm_fault+0xb38
[&lt;ffffffd4ffb9f008&gt;] do_page_fault+0x288
[&lt;ffffffd4ffb9ed64&gt;] do_translation_fault[jt]+0x40
[&lt;ffffffd4fec39c78&gt;] do_mem_abort+0x58
[&lt;ffffffd4ffb8c3e4&gt;] el0_ia+0x70
[&lt;ffffffd4ffb8c260&gt;] el0t_64_sync_handler[jt]+0xb0
[&lt;ffffffd4fec11588&gt;] ret_to_user[jt]+0x0

To fix this, introducee cpu within vmap_block to record which this vb
belongs to.

Link: https://lkml.kernel.org/r/20240614021352.1822225-1-zhaoyang.huang@unisoc.com
Link: https://lkml.kernel.org/r/20240607023116.1720640-1-zhaoyang.huang@unisoc.com
Fixes: fc1e0d980037 ("mm/vmalloc: prevent stale TLBs in fully utilized blocks")
Signed-off-by: Zhaoyang Huang &lt;zhaoyang.huang@unisoc.com&gt;
Suggested-by: Hailong.Liu &lt;hailong.liu@oppo.com&gt;
Reviewed-by: Uladzislau Rezki (Sony) &lt;urezki@gmail.com&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Lorenzo Stoakes &lt;lstoakes@gmail.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8c61291fd8500e3b35c7ec0c781b273d8cc96cde upstream.

xa_for_each() in _vm_unmap_aliases() loops through all vbs.  However,
since commit 062eacf57ad9 ("mm: vmalloc: remove a global vmap_blocks
xarray") the vb from xarray may not be on the corresponding CPU
vmap_block_queue.  Consequently, purge_fragmented_block() might use the
wrong vbq-&gt;lock to protect the free list, leading to vbq-&gt;free breakage.

Incorrect lock protection can exhaust all vmalloc space as follows:
CPU0                                            CPU1
+--------------------------------------------+
|    +--------------------+     +-----+      |
+--&gt; |                    |----&gt;|     |------+
     | CPU1:vbq free_list |     | vb1 |
+--- |                    |&lt;----|     |&lt;-----+
|    +--------------------+     +-----+      |
+--------------------------------------------+

_vm_unmap_aliases()                             vb_alloc()
                                                new_vmap_block()
xa_for_each(&amp;vbq-&gt;vmap_blocks, idx, vb)
--&gt; vb in CPU1:vbq-&gt;freelist

purge_fragmented_block(vb)
spin_lock(&amp;vbq-&gt;lock)                           spin_lock(&amp;vbq-&gt;lock)
--&gt; use CPU0:vbq-&gt;lock                          --&gt; use CPU1:vbq-&gt;lock

list_del_rcu(&amp;vb-&gt;free_list)                    list_add_tail_rcu(&amp;vb-&gt;free_list, &amp;vbq-&gt;free)
    __list_del(vb-&gt;prev, vb-&gt;next)
        next-&gt;prev = prev
    +--------------------+
    |                    |
    | CPU1:vbq free_list |
+---|                    |&lt;--+
|   +--------------------+   |
+----------------------------+
                                                __list_add(new, head-&gt;prev, head)
+--------------------------------------------+
|    +--------------------+     +-----+      |
+--&gt; |                    |----&gt;|     |------+
     | CPU1:vbq free_list |     | vb2 |
+--- |                    |&lt;----|     |&lt;-----+
|    +--------------------+     +-----+      |
+--------------------------------------------+

        prev-&gt;next = next
+--------------------------------------------+
|----------------------------+               |
|    +--------------------+  |  +-----+      |
+--&gt; |                    |--+  |     |------+
     | CPU1:vbq free_list |     | vb2 |
+--- |                    |&lt;----|     |&lt;-----+
|    +--------------------+     +-----+      |
+--------------------------------------------+
Here’s a list breakdown. All vbs, which were to be added to
‘prev’, cannot be used by list_for_each_entry_rcu(vb, &amp;vbq-&gt;free,
free_list) in vb_alloc(). Thus, vmalloc space is exhausted.

This issue affects both erofs and f2fs, the stacktrace is as follows:
erofs:
[&lt;ffffffd4ffb93ad4&gt;] __switch_to+0x174
[&lt;ffffffd4ffb942f0&gt;] __schedule+0x624
[&lt;ffffffd4ffb946f4&gt;] schedule+0x7c
[&lt;ffffffd4ffb947cc&gt;] schedule_preempt_disabled+0x24
[&lt;ffffffd4ffb962ec&gt;] __mutex_lock+0x374
[&lt;ffffffd4ffb95998&gt;] __mutex_lock_slowpath+0x14
[&lt;ffffffd4ffb95954&gt;] mutex_lock+0x24
[&lt;ffffffd4fef2900c&gt;] reclaim_and_purge_vmap_areas+0x44
[&lt;ffffffd4fef25908&gt;] alloc_vmap_area+0x2e0
[&lt;ffffffd4fef24ea0&gt;] vm_map_ram+0x1b0
[&lt;ffffffd4ff1b46f4&gt;] z_erofs_lz4_decompress+0x278
[&lt;ffffffd4ff1b8ac4&gt;] z_erofs_decompress_queue+0x650
[&lt;ffffffd4ff1b8328&gt;] z_erofs_runqueue+0x7f4
[&lt;ffffffd4ff1b66a8&gt;] z_erofs_read_folio+0x104
[&lt;ffffffd4feeb6fec&gt;] filemap_read_folio+0x6c
[&lt;ffffffd4feeb68c4&gt;] filemap_fault+0x300
[&lt;ffffffd4fef0ecac&gt;] __do_fault+0xc8
[&lt;ffffffd4fef0c908&gt;] handle_mm_fault+0xb38
[&lt;ffffffd4ffb9f008&gt;] do_page_fault+0x288
[&lt;ffffffd4ffb9ed64&gt;] do_translation_fault[jt]+0x40
[&lt;ffffffd4fec39c78&gt;] do_mem_abort+0x58
[&lt;ffffffd4ffb8c3e4&gt;] el0_ia+0x70
[&lt;ffffffd4ffb8c260&gt;] el0t_64_sync_handler[jt]+0xb0
[&lt;ffffffd4fec11588&gt;] ret_to_user[jt]+0x0

f2fs:
[&lt;ffffffd4ffb93ad4&gt;] __switch_to+0x174
[&lt;ffffffd4ffb942f0&gt;] __schedule+0x624
[&lt;ffffffd4ffb946f4&gt;] schedule+0x7c
[&lt;ffffffd4ffb947cc&gt;] schedule_preempt_disabled+0x24
[&lt;ffffffd4ffb962ec&gt;] __mutex_lock+0x374
[&lt;ffffffd4ffb95998&gt;] __mutex_lock_slowpath+0x14
[&lt;ffffffd4ffb95954&gt;] mutex_lock+0x24
[&lt;ffffffd4fef2900c&gt;] reclaim_and_purge_vmap_areas+0x44
[&lt;ffffffd4fef25908&gt;] alloc_vmap_area+0x2e0
[&lt;ffffffd4fef24ea0&gt;] vm_map_ram+0x1b0
[&lt;ffffffd4ff1a3b60&gt;] f2fs_prepare_decomp_mem+0x144
[&lt;ffffffd4ff1a6c24&gt;] f2fs_alloc_dic+0x264
[&lt;ffffffd4ff175468&gt;] f2fs_read_multi_pages+0x428
[&lt;ffffffd4ff17b46c&gt;] f2fs_mpage_readpages+0x314
[&lt;ffffffd4ff1785c4&gt;] f2fs_readahead+0x50
[&lt;ffffffd4feec3384&gt;] read_pages+0x80
[&lt;ffffffd4feec32c0&gt;] page_cache_ra_unbounded+0x1a0
[&lt;ffffffd4feec39e8&gt;] page_cache_ra_order+0x274
[&lt;ffffffd4feeb6cec&gt;] do_sync_mmap_readahead+0x11c
[&lt;ffffffd4feeb6764&gt;] filemap_fault+0x1a0
[&lt;ffffffd4ff1423bc&gt;] f2fs_filemap_fault+0x28
[&lt;ffffffd4fef0ecac&gt;] __do_fault+0xc8
[&lt;ffffffd4fef0c908&gt;] handle_mm_fault+0xb38
[&lt;ffffffd4ffb9f008&gt;] do_page_fault+0x288
[&lt;ffffffd4ffb9ed64&gt;] do_translation_fault[jt]+0x40
[&lt;ffffffd4fec39c78&gt;] do_mem_abort+0x58
[&lt;ffffffd4ffb8c3e4&gt;] el0_ia+0x70
[&lt;ffffffd4ffb8c260&gt;] el0t_64_sync_handler[jt]+0xb0
[&lt;ffffffd4fec11588&gt;] ret_to_user[jt]+0x0

To fix this, introducee cpu within vmap_block to record which this vb
belongs to.

Link: https://lkml.kernel.org/r/20240614021352.1822225-1-zhaoyang.huang@unisoc.com
Link: https://lkml.kernel.org/r/20240607023116.1720640-1-zhaoyang.huang@unisoc.com
Fixes: fc1e0d980037 ("mm/vmalloc: prevent stale TLBs in fully utilized blocks")
Signed-off-by: Zhaoyang Huang &lt;zhaoyang.huang@unisoc.com&gt;
Suggested-by: Hailong.Liu &lt;hailong.liu@oppo.com&gt;
Reviewed-by: Uladzislau Rezki (Sony) &lt;urezki@gmail.com&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Lorenzo Stoakes &lt;lstoakes@gmail.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/page_table_check: fix crash on ZONE_DEVICE</title>
<updated>2024-06-27T11:49:13+00:00</updated>
<author>
<name>Peter Xu</name>
<email>peterx@redhat.com</email>
</author>
<published>2024-06-05T21:21:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=84d3549d54f5ff9fa3281257be3019386f51d1a0'/>
<id>84d3549d54f5ff9fa3281257be3019386f51d1a0</id>
<content type='text'>
commit 8bb592c2eca8fd2bc06db7d80b38da18da4a2f43 upstream.

Not all pages may apply to pgtable check.  One example is ZONE_DEVICE
pages: they map PFNs directly, and they don't allocate page_ext at all
even if there's struct page around.  One may reference
devm_memremap_pages().

When both ZONE_DEVICE and page-table-check enabled, then try to map some
dax memories, one can trigger kernel bug constantly now when the kernel
was trying to inject some pfn maps on the dax device:

 kernel BUG at mm/page_table_check.c:55!

While it's pretty legal to use set_pxx_at() for ZONE_DEVICE pages for page
fault resolutions, skip all the checks if page_ext doesn't even exist in
pgtable checker, which applies to ZONE_DEVICE but maybe more.

Link: https://lkml.kernel.org/r/20240605212146.994486-1-peterx@redhat.com
Fixes: df4e817b7108 ("mm: page table check")
Signed-off-by: Peter Xu &lt;peterx@redhat.com&gt;
Reviewed-by: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Reviewed-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
Reviewed-by: Alistair Popple &lt;apopple@nvidia.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8bb592c2eca8fd2bc06db7d80b38da18da4a2f43 upstream.

Not all pages may apply to pgtable check.  One example is ZONE_DEVICE
pages: they map PFNs directly, and they don't allocate page_ext at all
even if there's struct page around.  One may reference
devm_memremap_pages().

When both ZONE_DEVICE and page-table-check enabled, then try to map some
dax memories, one can trigger kernel bug constantly now when the kernel
was trying to inject some pfn maps on the dax device:

 kernel BUG at mm/page_table_check.c:55!

While it's pretty legal to use set_pxx_at() for ZONE_DEVICE pages for page
fault resolutions, skip all the checks if page_ext doesn't even exist in
pgtable checker, which applies to ZONE_DEVICE but maybe more.

Link: https://lkml.kernel.org/r/20240605212146.994486-1-peterx@redhat.com
Fixes: df4e817b7108 ("mm: page table check")
Signed-off-by: Peter Xu &lt;peterx@redhat.com&gt;
Reviewed-by: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Reviewed-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
Reviewed-by: Alistair Popple &lt;apopple@nvidia.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/huge_memory: don't unpoison huge_zero_folio</title>
<updated>2024-06-21T12:38:46+00:00</updated>
<author>
<name>Miaohe Lin</name>
<email>linmiaohe@huawei.com</email>
</author>
<published>2024-05-16T12:26:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0d73477af964dbd7396163a13817baf13940bca9'/>
<id>0d73477af964dbd7396163a13817baf13940bca9</id>
<content type='text'>
commit fe6f86f4b40855a130a19aa589f9ba7f650423f4 upstream.

When I did memory failure tests recently, below panic occurs:

 kernel BUG at include/linux/mm.h:1135!
 invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
 CPU: 9 PID: 137 Comm: kswapd1 Not tainted 6.9.0-rc4-00491-gd5ce28f156fe-dirty #14
 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0
 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246
 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8
 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0
 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492
 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00
 FS:  0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0
 Call Trace:
  &lt;TASK&gt;
  do_shrink_slab+0x14f/0x6a0
  shrink_slab+0xca/0x8c0
  shrink_node+0x2d0/0x7d0
  balance_pgdat+0x33a/0x720
  kswapd+0x1f3/0x410
  kthread+0xd5/0x100
  ret_from_fork+0x2f/0x50
  ret_from_fork_asm+0x1a/0x30
  &lt;/TASK&gt;
 Modules linked in: mce_inject hwpoison_inject
 ---[ end trace 0000000000000000 ]---
 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0
 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246
 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8
 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0
 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492
 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00
 FS:  0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0

The root cause is that HWPoison flag will be set for huge_zero_folio
without increasing the folio refcnt.  But then unpoison_memory() will
decrease the folio refcnt unexpectedly as it appears like a successfully
hwpoisoned folio leading to VM_BUG_ON_PAGE(page_ref_count(page) == 0) when
releasing huge_zero_folio.

Skip unpoisoning huge_zero_folio in unpoison_memory() to fix this issue.
We're not prepared to unpoison huge_zero_folio yet.

Link: https://lkml.kernel.org/r/20240516122608.22610-1-linmiaohe@huawei.com
Fixes: 478d134e9506 ("mm/huge_memory: do not overkill when splitting huge_zero_page")
Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Yang Shi &lt;shy828301@gmail.com&gt;
Reviewed-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: Xu Yu &lt;xuyu@linux.alibaba.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit fe6f86f4b40855a130a19aa589f9ba7f650423f4 upstream.

When I did memory failure tests recently, below panic occurs:

 kernel BUG at include/linux/mm.h:1135!
 invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
 CPU: 9 PID: 137 Comm: kswapd1 Not tainted 6.9.0-rc4-00491-gd5ce28f156fe-dirty #14
 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0
 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246
 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8
 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0
 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492
 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00
 FS:  0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0
 Call Trace:
  &lt;TASK&gt;
  do_shrink_slab+0x14f/0x6a0
  shrink_slab+0xca/0x8c0
  shrink_node+0x2d0/0x7d0
  balance_pgdat+0x33a/0x720
  kswapd+0x1f3/0x410
  kthread+0xd5/0x100
  ret_from_fork+0x2f/0x50
  ret_from_fork_asm+0x1a/0x30
  &lt;/TASK&gt;
 Modules linked in: mce_inject hwpoison_inject
 ---[ end trace 0000000000000000 ]---
 RIP: 0010:shrink_huge_zero_page_scan+0x168/0x1a0
 RSP: 0018:ffff9933c6c57bd0 EFLAGS: 00000246
 RAX: 000000000000003e RBX: 0000000000000000 RCX: ffff88f61fc5c9c8
 RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff88f61fc5c9c0
 RBP: ffffcd7c446b0000 R08: ffffffff9a9405f0 R09: 0000000000005492
 R10: 00000000000030ea R11: ffffffff9a9405f0 R12: 0000000000000000
 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88e703c4ac00
 FS:  0000000000000000(0000) GS:ffff88f61fc40000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000055f4da6e9878 CR3: 0000000c71048000 CR4: 00000000000006f0

The root cause is that HWPoison flag will be set for huge_zero_folio
without increasing the folio refcnt.  But then unpoison_memory() will
decrease the folio refcnt unexpectedly as it appears like a successfully
hwpoisoned folio leading to VM_BUG_ON_PAGE(page_ref_count(page) == 0) when
releasing huge_zero_folio.

Skip unpoisoning huge_zero_folio in unpoison_memory() to fix this issue.
We're not prepared to unpoison huge_zero_folio yet.

Link: https://lkml.kernel.org/r/20240516122608.22610-1-linmiaohe@huawei.com
Fixes: 478d134e9506 ("mm/huge_memory: do not overkill when splitting huge_zero_page")
Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Yang Shi &lt;shy828301@gmail.com&gt;
Reviewed-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: Xu Yu &lt;xuyu@linux.alibaba.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/memory-failure: fix handling of dissolved but not taken off from buddy pages</title>
<updated>2024-06-21T12:38:21+00:00</updated>
<author>
<name>Miaohe Lin</name>
<email>linmiaohe@huawei.com</email>
</author>
<published>2024-05-23T07:12:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bb9bb13ce64cc7cae47f5e2ab9ce93b7bfa0117e'/>
<id>bb9bb13ce64cc7cae47f5e2ab9ce93b7bfa0117e</id>
<content type='text'>
[ Upstream commit 8cf360b9d6a840700e06864236a01a883b34bbad ]

When I did memory failure tests recently, below panic occurs:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00
flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff)
raw: 06fffe0000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000009 00000000ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(!PageBuddy(page))
------------[ cut here ]------------
kernel BUG at include/linux/page-flags.h:1009!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:__del_page_from_free_list+0x151/0x180
RSP: 0018:ffffa49c90437998 EFLAGS: 00000046
RAX: 0000000000000035 RBX: 0000000000000009 RCX: ffff8dd8dfd1c9c8
RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff8dd8dfd1c9c0
RBP: ffffd901233b8000 R08: ffffffffab5511f8 R09: 0000000000008c69
R10: 0000000000003c15 R11: ffffffffab5511f8 R12: ffff8dd8fffc0c80
R13: 0000000000000001 R14: ffff8dd8fffc0c80 R15: 0000000000000009
FS:  00007ff916304740(0000) GS:ffff8dd8dfd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055eae50124c8 CR3: 00000008479e0000 CR4: 00000000000006f0
Call Trace:
 &lt;TASK&gt;
 __rmqueue_pcplist+0x23b/0x520
 get_page_from_freelist+0x26b/0xe40
 __alloc_pages_noprof+0x113/0x1120
 __folio_alloc_noprof+0x11/0xb0
 alloc_buddy_hugetlb_folio.isra.0+0x5a/0x130
 __alloc_fresh_hugetlb_folio+0xe7/0x140
 alloc_pool_huge_folio+0x68/0x100
 set_max_huge_pages+0x13d/0x340
 hugetlb_sysctl_handler_common+0xe8/0x110
 proc_sys_call_handler+0x194/0x280
 vfs_write+0x387/0x550
 ksys_write+0x64/0xe0
 do_syscall_64+0xc2/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff916114887
RSP: 002b:00007ffec8a2fd78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055eae500e350 RCX: 00007ff916114887
RDX: 0000000000000004 RSI: 000055eae500e390 RDI: 0000000000000003
RBP: 000055eae50104c0 R08: 0000000000000000 R09: 000055eae50104c0
R10: 0000000000000077 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000000004 R14: 00007ff916216b80 R15: 00007ff916216a00
 &lt;/TASK&gt;
Modules linked in: mce_inject hwpoison_inject
---[ end trace 0000000000000000 ]---

And before the panic, there had an warning about bad page state:

BUG: Bad page state in process page-types  pfn:8cee00
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00
flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff)
page_type: 0xffffff7f(buddy)
raw: 06fffe0000000000 ffffd901241c0008 ffffd901240f8008 0000000000000000
raw: 0000000000000000 0000000000000009 00000000ffffff7f 0000000000000000
page dumped because: nonzero mapcount
Modules linked in: mce_inject hwpoison_inject
CPU: 8 PID: 154211 Comm: page-types Not tainted 6.9.0-rc4-00499-g5544ec3178e2-dirty #22
Call Trace:
 &lt;TASK&gt;
 dump_stack_lvl+0x83/0xa0
 bad_page+0x63/0xf0
 free_unref_page+0x36e/0x5c0
 unpoison_memory+0x50b/0x630
 simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110
 debugfs_attr_write+0x42/0x60
 full_proxy_write+0x5b/0x80
 vfs_write+0xcd/0x550
 ksys_write+0x64/0xe0
 do_syscall_64+0xc2/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f189a514887
RSP: 002b:00007ffdcd899718 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f189a514887
RDX: 0000000000000009 RSI: 00007ffdcd899730 RDI: 0000000000000003
RBP: 00007ffdcd8997a0 R08: 0000000000000000 R09: 00007ffdcd8994b2
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdcda199a8
R13: 0000000000404af1 R14: 000000000040ad78 R15: 00007f189a7a5040
 &lt;/TASK&gt;

The root cause should be the below race:

 memory_failure
  try_memory_failure_hugetlb
   me_huge_page
    __page_handle_poison
     dissolve_free_hugetlb_folio
     drain_all_pages -- Buddy page can be isolated e.g. for compaction.
     take_page_off_buddy -- Failed as page is not in the buddy list.
	     -- Page can be putback into buddy after compaction.
    page_ref_inc -- Leads to buddy page with refcnt = 1.

Then unpoison_memory() can unpoison the page and send the buddy page back
into buddy list again leading to the above bad page state warning.  And
bad_page() will call page_mapcount_reset() to remove PageBuddy from buddy
page leading to later VM_BUG_ON_PAGE(!PageBuddy(page)) when trying to
allocate this page.

Fix this issue by only treating __page_handle_poison() as successful when
it returns 1.

Link: https://lkml.kernel.org/r/20240523071217.1696196-1-linmiaohe@huawei.com
Fixes: ceaf8fbea79a ("mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage")
Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 8cf360b9d6a840700e06864236a01a883b34bbad ]

When I did memory failure tests recently, below panic occurs:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00
flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff)
raw: 06fffe0000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000009 00000000ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(!PageBuddy(page))
------------[ cut here ]------------
kernel BUG at include/linux/page-flags.h:1009!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:__del_page_from_free_list+0x151/0x180
RSP: 0018:ffffa49c90437998 EFLAGS: 00000046
RAX: 0000000000000035 RBX: 0000000000000009 RCX: ffff8dd8dfd1c9c8
RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff8dd8dfd1c9c0
RBP: ffffd901233b8000 R08: ffffffffab5511f8 R09: 0000000000008c69
R10: 0000000000003c15 R11: ffffffffab5511f8 R12: ffff8dd8fffc0c80
R13: 0000000000000001 R14: ffff8dd8fffc0c80 R15: 0000000000000009
FS:  00007ff916304740(0000) GS:ffff8dd8dfd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055eae50124c8 CR3: 00000008479e0000 CR4: 00000000000006f0
Call Trace:
 &lt;TASK&gt;
 __rmqueue_pcplist+0x23b/0x520
 get_page_from_freelist+0x26b/0xe40
 __alloc_pages_noprof+0x113/0x1120
 __folio_alloc_noprof+0x11/0xb0
 alloc_buddy_hugetlb_folio.isra.0+0x5a/0x130
 __alloc_fresh_hugetlb_folio+0xe7/0x140
 alloc_pool_huge_folio+0x68/0x100
 set_max_huge_pages+0x13d/0x340
 hugetlb_sysctl_handler_common+0xe8/0x110
 proc_sys_call_handler+0x194/0x280
 vfs_write+0x387/0x550
 ksys_write+0x64/0xe0
 do_syscall_64+0xc2/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff916114887
RSP: 002b:00007ffec8a2fd78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055eae500e350 RCX: 00007ff916114887
RDX: 0000000000000004 RSI: 000055eae500e390 RDI: 0000000000000003
RBP: 000055eae50104c0 R08: 0000000000000000 R09: 000055eae50104c0
R10: 0000000000000077 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000000004 R14: 00007ff916216b80 R15: 00007ff916216a00
 &lt;/TASK&gt;
Modules linked in: mce_inject hwpoison_inject
---[ end trace 0000000000000000 ]---

And before the panic, there had an warning about bad page state:

BUG: Bad page state in process page-types  pfn:8cee00
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8cee00
flags: 0x6fffe0000000000(node=1|zone=2|lastcpupid=0x7fff)
page_type: 0xffffff7f(buddy)
raw: 06fffe0000000000 ffffd901241c0008 ffffd901240f8008 0000000000000000
raw: 0000000000000000 0000000000000009 00000000ffffff7f 0000000000000000
page dumped because: nonzero mapcount
Modules linked in: mce_inject hwpoison_inject
CPU: 8 PID: 154211 Comm: page-types Not tainted 6.9.0-rc4-00499-g5544ec3178e2-dirty #22
Call Trace:
 &lt;TASK&gt;
 dump_stack_lvl+0x83/0xa0
 bad_page+0x63/0xf0
 free_unref_page+0x36e/0x5c0
 unpoison_memory+0x50b/0x630
 simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110
 debugfs_attr_write+0x42/0x60
 full_proxy_write+0x5b/0x80
 vfs_write+0xcd/0x550
 ksys_write+0x64/0xe0
 do_syscall_64+0xc2/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f189a514887
RSP: 002b:00007ffdcd899718 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f189a514887
RDX: 0000000000000009 RSI: 00007ffdcd899730 RDI: 0000000000000003
RBP: 00007ffdcd8997a0 R08: 0000000000000000 R09: 00007ffdcd8994b2
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdcda199a8
R13: 0000000000404af1 R14: 000000000040ad78 R15: 00007f189a7a5040
 &lt;/TASK&gt;

The root cause should be the below race:

 memory_failure
  try_memory_failure_hugetlb
   me_huge_page
    __page_handle_poison
     dissolve_free_hugetlb_folio
     drain_all_pages -- Buddy page can be isolated e.g. for compaction.
     take_page_off_buddy -- Failed as page is not in the buddy list.
	     -- Page can be putback into buddy after compaction.
    page_ref_inc -- Leads to buddy page with refcnt = 1.

Then unpoison_memory() can unpoison the page and send the buddy page back
into buddy list again leading to the above bad page state warning.  And
bad_page() will call page_mapcount_reset() to remove PageBuddy from buddy
page leading to later VM_BUG_ON_PAGE(!PageBuddy(page)) when trying to
allocate this page.

Fix this issue by only treating __page_handle_poison() as successful when
it returns 1.

Link: https://lkml.kernel.org/r/20240523071217.1696196-1-linmiaohe@huawei.com
Fixes: ceaf8fbea79a ("mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage")
Signed-off-by: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>memory-failure: use a folio in me_huge_page()</title>
<updated>2024-06-21T12:38:21+00:00</updated>
<author>
<name>Matthew Wilcox (Oracle)</name>
<email>willy@infradead.org</email>
</author>
<published>2023-11-17T16:14:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fe01748ca6d6ad25d31eaa61d155f5ecf80907cc'/>
<id>fe01748ca6d6ad25d31eaa61d155f5ecf80907cc</id>
<content type='text'>
[ Upstream commit b6fd410c32f1a66a52a42d6aae1ab7b011b74547 ]

This function was already explicitly calling compound_head();
unfortunately the compiler can't know that and elide the redundant calls
to compound_head() buried in page_mapping(), unlock_page(), etc.  Switch
to using a folio, which does let us elide these calls.

Link: https://lkml.kernel.org/r/20231117161447.2461643-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Stable-dep-of: 8cf360b9d6a8 ("mm/memory-failure: fix handling of dissolved but not taken off from buddy pages")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b6fd410c32f1a66a52a42d6aae1ab7b011b74547 ]

This function was already explicitly calling compound_head();
unfortunately the compiler can't know that and elide the redundant calls
to compound_head() buried in page_mapping(), unlock_page(), etc.  Switch
to using a folio, which does let us elide these calls.

Link: https://lkml.kernel.org/r/20231117161447.2461643-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Naoya Horiguchi &lt;naoya.horiguchi@nec.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Stable-dep-of: 8cf360b9d6a8 ("mm/memory-failure: fix handling of dissolved but not taken off from buddy pages")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL</title>
<updated>2024-06-16T11:47:42+00:00</updated>
<author>
<name>Hailong.Liu</name>
<email>hailong.liu@oppo.com</email>
</author>
<published>2024-05-10T10:01:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c55d3564ad25ce87ab7cc6af251f9574faebd8da'/>
<id>c55d3564ad25ce87ab7cc6af251f9574faebd8da</id>
<content type='text'>
commit 8e0545c83d672750632f46e3f9ad95c48c91a0fc upstream.

commit a421ef303008 ("mm: allow !GFP_KERNEL allocations for kvmalloc")
includes support for __GFP_NOFAIL, but it presents a conflict with commit
dd544141b9eb ("vmalloc: back off when the current task is OOM-killed").  A
possible scenario is as follows:

process-a
__vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL)
    __vmalloc_area_node()
        vm_area_alloc_pages()
		--&gt; oom-killer send SIGKILL to process-a
        if (fatal_signal_pending(current)) break;
--&gt; return NULL;

To fix this, do not check fatal_signal_pending() in vm_area_alloc_pages()
if __GFP_NOFAIL set.

This issue occurred during OPLUS KASAN TEST. Below is part of the log
-&gt; oom-killer sends signal to process
[65731.222840] [ T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/uid_10198,task=gs.intelligence,pid=32454,uid=10198

[65731.259685] [T32454] Call trace:
[65731.259698] [T32454]  dump_backtrace+0xf4/0x118
[65731.259734] [T32454]  show_stack+0x18/0x24
[65731.259756] [T32454]  dump_stack_lvl+0x60/0x7c
[65731.259781] [T32454]  dump_stack+0x18/0x38
[65731.259800] [T32454]  mrdump_common_die+0x250/0x39c [mrdump]
[65731.259936] [T32454]  ipanic_die+0x20/0x34 [mrdump]
[65731.260019] [T32454]  atomic_notifier_call_chain+0xb4/0xfc
[65731.260047] [T32454]  notify_die+0x114/0x198
[65731.260073] [T32454]  die+0xf4/0x5b4
[65731.260098] [T32454]  die_kernel_fault+0x80/0x98
[65731.260124] [T32454]  __do_kernel_fault+0x160/0x2a8
[65731.260146] [T32454]  do_bad_area+0x68/0x148
[65731.260174] [T32454]  do_mem_abort+0x151c/0x1b34
[65731.260204] [T32454]  el1_abort+0x3c/0x5c
[65731.260227] [T32454]  el1h_64_sync_handler+0x54/0x90
[65731.260248] [T32454]  el1h_64_sync+0x68/0x6c

[65731.260269] [T32454]  z_erofs_decompress_queue+0x7f0/0x2258
--&gt; be-&gt;decompressed_pages = kvcalloc(be-&gt;nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL);
	kernel panic by NULL pointer dereference.
	erofs assume kvmalloc with __GFP_NOFAIL never return NULL.
[65731.260293] [T32454]  z_erofs_runqueue+0xf30/0x104c
[65731.260314] [T32454]  z_erofs_readahead+0x4f0/0x968
[65731.260339] [T32454]  read_pages+0x170/0xadc
[65731.260364] [T32454]  page_cache_ra_unbounded+0x874/0xf30
[65731.260388] [T32454]  page_cache_ra_order+0x24c/0x714
[65731.260411] [T32454]  filemap_fault+0xbf0/0x1a74
[65731.260437] [T32454]  __do_fault+0xd0/0x33c
[65731.260462] [T32454]  handle_mm_fault+0xf74/0x3fe0
[65731.260486] [T32454]  do_mem_abort+0x54c/0x1b34
[65731.260509] [T32454]  el0_da+0x44/0x94
[65731.260531] [T32454]  el0t_64_sync_handler+0x98/0xb4
[65731.260553] [T32454]  el0t_64_sync+0x198/0x19c

Link: https://lkml.kernel.org/r/20240510100131.1865-1-hailong.liu@oppo.com
Fixes: 9376130c390a ("mm/vmalloc: add support for __GFP_NOFAIL")
Signed-off-by: Hailong.Liu &lt;hailong.liu@oppo.com&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Suggested-by: Barry Song &lt;21cnbao@gmail.com&gt;
Reported-by: Oven &lt;liyangouwen1@oppo.com&gt;
Reviewed-by: Barry Song &lt;baohua@kernel.org&gt;
Reviewed-by: Uladzislau Rezki (Sony) &lt;urezki@gmail.com&gt;
Cc: Chao Yu &lt;chao@kernel.org&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Gao Xiang &lt;xiang@kernel.org&gt;
Cc: Lorenzo Stoakes &lt;lstoakes@gmail.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8e0545c83d672750632f46e3f9ad95c48c91a0fc upstream.

commit a421ef303008 ("mm: allow !GFP_KERNEL allocations for kvmalloc")
includes support for __GFP_NOFAIL, but it presents a conflict with commit
dd544141b9eb ("vmalloc: back off when the current task is OOM-killed").  A
possible scenario is as follows:

process-a
__vmalloc_node_range(GFP_KERNEL | __GFP_NOFAIL)
    __vmalloc_area_node()
        vm_area_alloc_pages()
		--&gt; oom-killer send SIGKILL to process-a
        if (fatal_signal_pending(current)) break;
--&gt; return NULL;

To fix this, do not check fatal_signal_pending() in vm_area_alloc_pages()
if __GFP_NOFAIL set.

This issue occurred during OPLUS KASAN TEST. Below is part of the log
-&gt; oom-killer sends signal to process
[65731.222840] [ T1308] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/apps/uid_10198,task=gs.intelligence,pid=32454,uid=10198

[65731.259685] [T32454] Call trace:
[65731.259698] [T32454]  dump_backtrace+0xf4/0x118
[65731.259734] [T32454]  show_stack+0x18/0x24
[65731.259756] [T32454]  dump_stack_lvl+0x60/0x7c
[65731.259781] [T32454]  dump_stack+0x18/0x38
[65731.259800] [T32454]  mrdump_common_die+0x250/0x39c [mrdump]
[65731.259936] [T32454]  ipanic_die+0x20/0x34 [mrdump]
[65731.260019] [T32454]  atomic_notifier_call_chain+0xb4/0xfc
[65731.260047] [T32454]  notify_die+0x114/0x198
[65731.260073] [T32454]  die+0xf4/0x5b4
[65731.260098] [T32454]  die_kernel_fault+0x80/0x98
[65731.260124] [T32454]  __do_kernel_fault+0x160/0x2a8
[65731.260146] [T32454]  do_bad_area+0x68/0x148
[65731.260174] [T32454]  do_mem_abort+0x151c/0x1b34
[65731.260204] [T32454]  el1_abort+0x3c/0x5c
[65731.260227] [T32454]  el1h_64_sync_handler+0x54/0x90
[65731.260248] [T32454]  el1h_64_sync+0x68/0x6c

[65731.260269] [T32454]  z_erofs_decompress_queue+0x7f0/0x2258
--&gt; be-&gt;decompressed_pages = kvcalloc(be-&gt;nr_pages, sizeof(struct page *), GFP_KERNEL | __GFP_NOFAIL);
	kernel panic by NULL pointer dereference.
	erofs assume kvmalloc with __GFP_NOFAIL never return NULL.
[65731.260293] [T32454]  z_erofs_runqueue+0xf30/0x104c
[65731.260314] [T32454]  z_erofs_readahead+0x4f0/0x968
[65731.260339] [T32454]  read_pages+0x170/0xadc
[65731.260364] [T32454]  page_cache_ra_unbounded+0x874/0xf30
[65731.260388] [T32454]  page_cache_ra_order+0x24c/0x714
[65731.260411] [T32454]  filemap_fault+0xbf0/0x1a74
[65731.260437] [T32454]  __do_fault+0xd0/0x33c
[65731.260462] [T32454]  handle_mm_fault+0xf74/0x3fe0
[65731.260486] [T32454]  do_mem_abort+0x54c/0x1b34
[65731.260509] [T32454]  el0_da+0x44/0x94
[65731.260531] [T32454]  el0t_64_sync_handler+0x98/0xb4
[65731.260553] [T32454]  el0t_64_sync+0x198/0x19c

Link: https://lkml.kernel.org/r/20240510100131.1865-1-hailong.liu@oppo.com
Fixes: 9376130c390a ("mm/vmalloc: add support for __GFP_NOFAIL")
Signed-off-by: Hailong.Liu &lt;hailong.liu@oppo.com&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Suggested-by: Barry Song &lt;21cnbao@gmail.com&gt;
Reported-by: Oven &lt;liyangouwen1@oppo.com&gt;
Reviewed-by: Barry Song &lt;baohua@kernel.org&gt;
Reviewed-by: Uladzislau Rezki (Sony) &lt;urezki@gmail.com&gt;
Cc: Chao Yu &lt;chao@kernel.org&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Gao Xiang &lt;xiang@kernel.org&gt;
Cc: Lorenzo Stoakes &lt;lstoakes@gmail.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/hugetlb: pass correct order_per_bit to cma_declare_contiguous_nid</title>
<updated>2024-06-16T11:47:42+00:00</updated>
<author>
<name>Frank van der Linden</name>
<email>fvdl@google.com</email>
</author>
<published>2024-04-04T16:25:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cb3ea7684a437283dbe4ec889f432fa45f7731be'/>
<id>cb3ea7684a437283dbe4ec889f432fa45f7731be</id>
<content type='text'>
commit 55d134a7b499c77e7cfd0ee41046f3c376e791e5 upstream.

The hugetlb_cma code passes 0 in the order_per_bit argument to
cma_declare_contiguous_nid (the alignment, computed using the page order,
is correctly passed in).

This causes a bit in the cma allocation bitmap to always represent a 4k
page, making the bitmaps potentially very large, and slower.

It would create bitmaps that would be pretty big.  E.g.  for a 4k page
size on x86, hugetlb_cma=64G would mean a bitmap size of (64G / 4k) / 8
== 2M.  With HUGETLB_PAGE_ORDER as order_per_bit, as intended, this
would be (64G / 2M) / 8 == 4k.  So, that's quite a difference.

Also, this restricted the hugetlb_cma area to ((PAGE_SIZE &lt;&lt;
MAX_PAGE_ORDER) * 8) * PAGE_SIZE (e.g.  128G on x86) , since
bitmap_alloc uses normal page allocation, and is thus restricted by
MAX_PAGE_ORDER.  Specifying anything about that would fail the CMA
initialization.

So, correctly pass in the order instead.

Link: https://lkml.kernel.org/r/20240404162515.527802-2-fvdl@google.com
Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Signed-off-by: Frank van der Linden &lt;fvdl@google.com&gt;
Acked-by: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 55d134a7b499c77e7cfd0ee41046f3c376e791e5 upstream.

The hugetlb_cma code passes 0 in the order_per_bit argument to
cma_declare_contiguous_nid (the alignment, computed using the page order,
is correctly passed in).

This causes a bit in the cma allocation bitmap to always represent a 4k
page, making the bitmaps potentially very large, and slower.

It would create bitmaps that would be pretty big.  E.g.  for a 4k page
size on x86, hugetlb_cma=64G would mean a bitmap size of (64G / 4k) / 8
== 2M.  With HUGETLB_PAGE_ORDER as order_per_bit, as intended, this
would be (64G / 2M) / 8 == 4k.  So, that's quite a difference.

Also, this restricted the hugetlb_cma area to ((PAGE_SIZE &lt;&lt;
MAX_PAGE_ORDER) * 8) * PAGE_SIZE (e.g.  128G on x86) , since
bitmap_alloc uses normal page allocation, and is thus restricted by
MAX_PAGE_ORDER.  Specifying anything about that would fail the CMA
initialization.

So, correctly pass in the order instead.

Link: https://lkml.kernel.org/r/20240404162515.527802-2-fvdl@google.com
Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Signed-off-by: Frank van der Linden &lt;fvdl@google.com&gt;
Acked-by: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/cma: drop incorrect alignment check in cma_init_reserved_mem</title>
<updated>2024-06-16T11:47:42+00:00</updated>
<author>
<name>Frank van der Linden</name>
<email>fvdl@google.com</email>
</author>
<published>2024-04-04T16:25:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f317e97da981085b2aab282e50592701ff8721ae'/>
<id>f317e97da981085b2aab282e50592701ff8721ae</id>
<content type='text'>
commit b174f139bdc8aaaf72f5b67ad1bd512c4868a87e upstream.

cma_init_reserved_mem uses IS_ALIGNED to check if the size represented by
one bit in the cma allocation bitmask is aligned with
CMA_MIN_ALIGNMENT_BYTES (pageblock size).

However, this is too strict, as this will fail if order_per_bit &gt;
pageblock_order, which is a valid configuration.

We could check IS_ALIGNED both ways, but since both numbers are powers of
two, no check is needed at all.

Link: https://lkml.kernel.org/r/20240404162515.527802-1-fvdl@google.com
Fixes: de9e14eebf33 ("drivers: dma-contiguous: add initialization from device tree")
Signed-off-by: Frank van der Linden &lt;fvdl@google.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b174f139bdc8aaaf72f5b67ad1bd512c4868a87e upstream.

cma_init_reserved_mem uses IS_ALIGNED to check if the size represented by
one bit in the cma allocation bitmask is aligned with
CMA_MIN_ALIGNMENT_BYTES (pageblock size).

However, this is too strict, as this will fail if order_per_bit &gt;
pageblock_order, which is a valid configuration.

We could check IS_ALIGNED both ways, but since both numbers are powers of
two, no check is needed at all.

Link: https://lkml.kernel.org/r/20240404162515.527802-1-fvdl@google.com
Fixes: de9e14eebf33 ("drivers: dma-contiguous: add initialization from device tree")
Signed-off-by: Frank van der Linden &lt;fvdl@google.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kmsan: do not wipe out origin when doing partial unpoisoning</title>
<updated>2024-06-16T11:47:41+00:00</updated>
<author>
<name>Alexander Potapenko</name>
<email>glider@google.com</email>
</author>
<published>2024-05-28T10:48:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=19e85d939001946671643f4c16e1de8c633a6ce0'/>
<id>19e85d939001946671643f4c16e1de8c633a6ce0</id>
<content type='text'>
commit 2ef3cec44c60ae171b287db7fc2aa341586d65ba upstream.

As noticed by Brian, KMSAN should not be zeroing the origin when
unpoisoning parts of a four-byte uninitialized value, e.g.:

    char a[4];
    kmsan_unpoison_memory(a, 1);

This led to false negatives, as certain poisoned values could receive zero
origins, preventing those values from being reported.

To fix the problem, check that kmsan_internal_set_shadow_origin() writes
zero origins only to slots which have zero shadow.

Link: https://lkml.kernel.org/r/20240528104807.738758-1-glider@google.com
Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
Signed-off-by: Alexander Potapenko &lt;glider@google.com&gt;
Reported-by: Brian Johannesmeyer &lt;bjohannesmeyer@gmail.com&gt;
  Link: https://lore.kernel.org/lkml/20240524232804.1984355-1-bjohannesmeyer@gmail.com/T/
Reviewed-by: Marco Elver &lt;elver@google.com&gt;
Tested-by: Brian Johannesmeyer &lt;bjohannesmeyer@gmail.com&gt;
Cc: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 2ef3cec44c60ae171b287db7fc2aa341586d65ba upstream.

As noticed by Brian, KMSAN should not be zeroing the origin when
unpoisoning parts of a four-byte uninitialized value, e.g.:

    char a[4];
    kmsan_unpoison_memory(a, 1);

This led to false negatives, as certain poisoned values could receive zero
origins, preventing those values from being reported.

To fix the problem, check that kmsan_internal_set_shadow_origin() writes
zero origins only to slots which have zero shadow.

Link: https://lkml.kernel.org/r/20240528104807.738758-1-glider@google.com
Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
Signed-off-by: Alexander Potapenko &lt;glider@google.com&gt;
Reported-by: Brian Johannesmeyer &lt;bjohannesmeyer@gmail.com&gt;
  Link: https://lore.kernel.org/lkml/20240524232804.1984355-1-bjohannesmeyer@gmail.com/T/
Reviewed-by: Marco Elver &lt;elver@google.com&gt;
Tested-by: Brian Johannesmeyer &lt;bjohannesmeyer@gmail.com&gt;
Cc: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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