Stressing huge tmpfs often crashed on unmap_page()'s VM_BUG_ON_PAGE
(!unmap_success): with dump_page() showing mapcount:1, but then its raw
struct page output showing _mapcount ffffffff i.e.  mapcount 0.

And even if that particular VM_BUG_ON_PAGE(!unmap_success) is removed,
it is immediately followed by a VM_BUG_ON_PAGE(compound_mapcount(head)),
and further down an IS_ENABLED(CONFIG_DEBUG_VM) total_mapcount BUG():
all indicative of some mapcount difficulty in development here perhaps.
But the !CONFIG_DEBUG_VM path handles the failures correctly and
silently.

I believe the problem is that once a racing unmap has cleared pte or
pmd, try_to_unmap_one() may skip taking the page table lock, and emerge
from try_to_unmap() before the racing task has reached decrementing
mapcount.

Instead of abandoning the unsafe VM_BUG_ON_PAGE(), and the ones that
follow, use PVMW_SYNC in try_to_unmap_one() in this case: adding
TTU_SYNC to the options, and passing that from unmap_page().

When CONFIG_DEBUG_VM, or for non-debug too? Consensus is to do the same
for both: the slight overhead added should rarely matter, except perhaps
if splitting sparsely-populated multiply-mapped shmem.  Once confident
that bugs are fixed, TTU_SYNC here can be removed, and the race
tolerated.

Link: https://lkml.kernel.org/r/c1e95853-8bcd-d8fd-55fa-e7f2488e78f@google.com
Fixes: fec89c10 ("thp: rewrite freeze_page()/unfreeze_page() with generic rmap walkers")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jue Wang <juew@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Most callers of is_huge_zero_pmd() supply a pmd already verified
present; but a few (notably zap_huge_pmd()) do not - it might be a pmd
migration entry, in which the pfn is encoded differently from a present
pmd: which might pass the is_huge_zero_pmd() test (though not on x86,
since L1TF forced us to protect against that); or perhaps even crash in
pmd_page() applied to a swap-like entry.

Make it safe by adding pmd_present() check into is_huge_zero_pmd()
itself; and make it quicker by saving huge_zero_pfn, so that
is_huge_zero_pmd() will not need to do that pmd_page() lookup each time.

__split_huge_pmd_locked() checked pmd_trans_huge() before: that worked,
but is unnecessary now that is_huge_zero_pmd() checks present.

Link: https://lkml.kernel.org/r/21ea9ca-a1f5-8b90-5e88-95fb1c49bbfa@google.com
Fixes: e71769ae ("mm: enable thp migration for shmem thp")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jue Wang <juew@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "mm/thp: fix THP splitting unmap BUGs and related", v10.

Here is v2 batch of long-standing THP bug fixes that I had not got
around to sending before, but prompted now by Wang Yugui's report
https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/

Wang Yugui has tested a rollup of these fixes applied to 5.10.39, and
they have done no harm, but have *not* fixed that issue: something more
is needed and I have no idea of what.

This patch (of 7):

Stressing huge tmpfs page migration racing hole punch often crashed on
the VM_BUG_ON(!pmd_present) in pmdp_huge_clear_flush(), with DEBUG_VM=y
kernel; or shortly afterwards, on a bad dereference in
__split_huge_pmd_locked() when DEBUG_VM=n.  They forgot to allow for pmd
migration entries in the non-anonymous case.

Full disclosure: those particular experiments were on a kernel with more
relaxed mmap_lock and i_mmap_rwsem locking, and were not repeated on the
vanilla kernel: it is conceivable that stricter locking happens to avoid
those cases, or makes them less likely; but __split_huge_pmd_locked()
already allowed for pmd migration entries when handling anonymous THPs,
so this commit brings the shmem and file THP handling into line.

And while there: use old_pmd rather than _pmd, as in the following
blocks; and make it clearer to the eye that the !vma_is_anonymous()
block is self-contained, making an early return after accounting for
unmapping.

Link: https://lkml.kernel.org/r/af88612-1473-2eaa-903-8d1a448b26@google.com
Link: https://lkml.kernel.org/r/dd221a99-efb3-cd1d-6256-7e646af29314@google.com
Fixes: e71769ae ("mm: enable thp migration for shmem thp")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jue Wang <juew@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We notice that hung task happens in a corner but practical scenario when
CONFIG_PREEMPT_NONE is enabled, as follows.

Process 0                       Process 1                     Process 2..Inf
split_huge_page_to_list
    unmap_page
        split_huge_pmd_address
                                __migration_entry_wait(head)
                                                              __migration_entry_wait(tail)
    remap_page (roll back)
        remove_migration_ptes
            rmap_walk_anon
                cond_resched

Where __migration_entry_wait(tail) is occurred in kernel space, e.g.,
copy_to_user in fstat, which will immediately fault again without
rescheduling, and thus occupy the cpu fully.

When there are too many processes performing __migration_entry_wait on
tail page, remap_page will never be done after cond_resched.

This makes __migration_entry_wait operate on the compound head page,
thus waits for remap_page to complete, whether the THP is split
successfully or roll back.

Note that put_and_wait_on_page_locked helps to drop the page reference
acquired with get_page_unless_zero, as soon as the page is on the wait
queue, before actually waiting.  So splitting the THP is only prevented
for a brief interval.

Link: https://lkml.kernel.org/r/b9836c1dd522e903891760af9f0c86a2cce987eb.1623144009.git.xuyu@linux.alibaba.com
Fixes: ba988280 ("thp: add option to setup migration entries during PMD split")
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Gang Deng <gavin.dg@linux.alibaba.com>
Signed-off-by: Xu Yu <xuyu@linux.alibaba.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fixes build with CONFIG_SLAB_FREELIST_HARDENED=y.

Hopefully.  But it's the right thing to do anwyay.

Fixes: 1ad53d9f ("slub: improve bit diffusion for freelist ptr obfuscation")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213417
Reported-by: <vannguye@cisco.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

As mentioned in kernel commit 1d50e5d0 ("crash_core, vmcoreinfo:
Append 'MAX_PHYSMEM_BITS' to vmcoreinfo"), SECTION_SIZE_BITS in the
formula:

    #define SECTIONS_SHIFT    (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)

Besides SECTIONS_SHIFT, SECTION_SIZE_BITS is also used to calculate
PAGES_PER_SECTION in makedumpfile just like kernel.

Unfortunately, this arch-dependent macro SECTION_SIZE_BITS changes, e.g.
recently in kernel commit f0b13ee2 ("arm64/sparsemem: reduce
SECTION_SIZE_BITS").  But user space wants a stable interface to get
this info.  Such info is impossible to be deduced from a crashdump
vmcore.  Hence append SECTION_SIZE_BITS to vmcoreinfo.

Link: https://lkml.kernel.org/r/20210608103359.84907-1-kernelfans@gmail.com
Link: http://lists.infradead.org/pipermail/kexec/2021-June/022676.htmlSigned-off-by: Pingfan Liu <kernelfans@gmail.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Boris Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Anderson <anderson@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Our syzkaller trigger the "BUG_ON(!list_empty(&inode->i_wb_list))" in
clear_inode:

  kernel BUG at fs/inode.c:519!
  Internal error: Oops - BUG: 0 [#1] SMP
  Modules linked in:
  Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7)
  CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95
  Hardware name: linux,dummy-virt (DT)
  pstate: 80000005 (Nzcv daif -PAN -UAO)
  pc : clear_inode+0x280/0x2a8
  lr : clear_inode+0x280/0x2a8
  Call trace:
    clear_inode+0x280/0x2a8
    ext4_clear_inode+0x38/0xe8
    ext4_free_inode+0x130/0xc68
    ext4_evict_inode+0xb20/0xcb8
    evict+0x1a8/0x3c0
    iput+0x344/0x460
    do_unlinkat+0x260/0x410
    __arm64_sys_unlinkat+0x6c/0xc0
    el0_svc_common+0xdc/0x3b0
    el0_svc_handler+0xf8/0x160
    el0_svc+0x10/0x218
  Kernel panic - not syncing: Fatal exception

A crash dump of this problem show that someone called __munlock_pagevec
to clear page LRU without lock_page: do_mmap -> mmap_region -> do_munmap
-> munlock_vma_pages_range -> __munlock_pagevec.

As a result memory_failure will call identify_page_state without
wait_on_page_writeback.  And after truncate_error_page clear the mapping
of this page.  end_page_writeback won't call sb_clear_inode_writeback to
clear inode->i_wb_list.  That will trigger BUG_ON in clear_inode!

Fix it by checking PageWriteback too to help determine should we skip
wait_on_page_writeback.

Link: https://lkml.kernel.org/r/20210604084705.3729204-1-yangerkun@huawei.com
Fixes: 0bc1f8b0 ("hwpoison: fix the handling path of the victimized page frame that belong to non-LRU")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The routine restore_reserve_on_error is called to restore reservation
information when an error occurs after page allocation.  The routine
alloc_huge_page modifies the mapping reserve map and potentially the
reserve count during allocation.  If code calling alloc_huge_page
encounters an error after allocation and needs to free the page, the
reservation information needs to be adjusted.

Currently, restore_reserve_on_error only takes action on pages for which
the reserve count was adjusted(HPageRestoreReserve flag).  There is
nothing wrong with these adjustments.  However, alloc_huge_page ALWAYS
modifies the reserve map during allocation even if the reserve count is
not adjusted.  This can cause issues as observed during development of
this patch [1].

One specific series of operations causing an issue is:

 - Create a shared hugetlb mapping
   Reservations for all pages created by default

 - Fault in a page in the mapping
   Reservation exists so reservation count is decremented

 - Punch a hole in the file/mapping at index previously faulted
   Reservation and any associated pages will be removed

 - Allocate a page to fill the hole
   No reservation entry, so reserve count unmodified
   Reservation entry added to map by alloc_huge_page

 - Error after allocation and before instantiating the page
   Reservation entry remains in map

 - Allocate a page to fill the hole
   Reservation entry exists, so decrement reservation count

This will cause a reservation count underflow as the reservation count
was decremented twice for the same index.

A user would observe a very large number for HugePages_Rsvd in
/proc/meminfo.  This would also likely cause subsequent allocations of
hugetlb pages to fail as it would 'appear' that all pages are reserved.

This sequence of operations is unlikely to happen, however they were
easily reproduced and observed using hacked up code as described in [1].

Address the issue by having the routine restore_reserve_on_error take
action on pages where HPageRestoreReserve is not set.  In this case, we
need to remove any reserve map entry created by alloc_huge_page.  A new
helper routine vma_del_reservation assists with this operation.

There are three callers of alloc_huge_page which do not currently call
restore_reserve_on error before freeing a page on error paths.  Add
those missing calls.

[1] https://lore.kernel.org/linux-mm/20210528005029.88088-1-almasrymina@google.com/

Link: https://lkml.kernel.org/r/20210607204510.22617-1-mike.kravetz@oracle.com
Fixes: 96b96a96 ("mm/hugetlb: fix huge page reservation leak in private mapping error paths"
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

It turns out that SLUB redzoning ("slub_debug=Z") checks from
s->object_size rather than from s->inuse (which is normally bumped to
make room for the freelist pointer), so a cache created with an object
size less than 24 would have the freelist pointer written beyond
s->object_size, causing the redzone to be corrupted by the freelist
pointer.  This was very visible with "slub_debug=ZF":

  BUG test (Tainted: G    B            ): Right Redzone overwritten
  -----------------------------------------------------------------------------

  INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb
  INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200
  INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620

  Redzone  (____ptrval____): bb bb bb bb bb bb bb bb               ........
  Object   (____ptrval____): 00 00 00 00 00 f6 f4 a5               ........
  Redzone  (____ptrval____): 40 1d e8 1a aa                        @....
  Padding  (____ptrval____): 00 00 00 00 00 00 00 00               ........

Adjust the offset to stay within s->object_size.

(Note that no caches of in this size range are known to exist in the
kernel currently.)

Link: https://lkml.kernel.org/r/20210608183955.280836-4-keescook@chromium.org
Link: https://lore.kernel.org/linux-mm/20200807160627.GA1420741@elver.google.com/
Link: https://lore.kernel.org/lkml/0f7dd7b2-7496-5e2d-9488-2ec9f8e90441@suse.cz/Fixes: 89b83f28 (slub: avoid redzone when choosing freepointer location)
Link: https://lore.kernel.org/lkml/CANpmjNOwZ5VpKQn+SYWovTkFB4VsT-RPwyENBmaK0dLcpqStkA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Marco Elver <elver@google.com>
Reported-by: "Lin, Zhenpeng" <zplin@psu.edu>
Tested-by: Marco Elver <elver@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The redzone area for SLUB exists between s->object_size and s->inuse
(which is at least the word-aligned object_size).  If a cache were
created with an object_size smaller than sizeof(void *), the in-object
stored freelist pointer would overwrite the redzone (e.g.  with boot
param "slub_debug=ZF"):

  BUG test (Tainted: G    B            ): Right Redzone overwritten
  -----------------------------------------------------------------------------

  INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb
  INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200
  INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620

  Redzone  (____ptrval____): bb bb bb bb bb bb bb bb    ........
  Object   (____ptrval____): f6 f4 a5 40 1d e8          ...@..
  Redzone  (____ptrval____): 1a aa                      ..
  Padding  (____ptrval____): 00 00 00 00 00 00 00 00    ........

Store the freelist pointer out of line when object_size is smaller than
sizeof(void *) and redzoning is enabled.

Additionally remove the "smaller than sizeof(void *)" check under
CONFIG_DEBUG_VM in kmem_cache_sanity_check() as it is now redundant:
SLAB and SLOB both handle small sizes.

(Note that no caches within this size range are known to exist in the
kernel currently.)

Link: https://lkml.kernel.org/r/20210608183955.280836-3-keescook@chromium.org
Fixes: 81819f0f ("SLUB core")
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Lin, Zhenpeng" <zplin@psu.edu>
Cc: Marco Elver <elver@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "Actually fix freelist pointer vs redzoning", v4.

This fixes redzoning vs the freelist pointer (both for middle-position
and very small caches).  Both are "theoretical" fixes, in that I see no
evidence of such small-sized caches actually be used in the kernel, but
that's no reason to let the bugs continue to exist, especially since
people doing local development keep tripping over it.  :)

This patch (of 3):

Instead of repeating "Redzone" and "Poison", clarify which sides of
those zones got tripped.  Additionally fix column alignment in the
trailer.

Before:

  BUG test (Tainted: G    B            ): Redzone overwritten
  ...
  Redzone (____ptrval____): bb bb bb bb bb bb bb bb      ........
  Object (____ptrval____): f6 f4 a5 40 1d e8            ...@..
  Redzone (____ptrval____): 1a aa                        ..
  Padding (____ptrval____): 00 00 00 00 00 00 00 00      ........

After:

  BUG test (Tainted: G    B            ): Right Redzone overwritten
  ...
  Redzone  (____ptrval____): bb bb bb bb bb bb bb bb      ........
  Object   (____ptrval____): f6 f4 a5 40 1d e8            ...@..
  Redzone  (____ptrval____): 1a aa                        ..
  Padding  (____ptrval____): 00 00 00 00 00 00 00 00      ........

The earlier commits that slowly resulted in the "Before" reporting were:

  d86bd1be ("mm/slub: support left redzone")
  ffc79d28 ("slub: use print_hex_dump")
  24922684 ("SLUB: change error reporting format to follow lockdep loosely")

Link: https://lkml.kernel.org/r/20210608183955.280836-1-keescook@chromium.org
Link: https://lkml.kernel.org/r/20210608183955.280836-2-keescook@chromium.org
Link: https://lore.kernel.org/lkml/cfdb11d7-fb8e-e578-c939-f7f5fb69a6bd@suse.cz/Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marco Elver <elver@google.com>
Cc: "Lin, Zhenpeng" <zplin@psu.edu>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I found it by pure code review, that pte_same_as_swp() of unuse_vma()
didn't take uffd-wp bit into account when comparing ptes.
pte_same_as_swp() returning false negative could cause failure to
swapoff swap ptes that was wr-protected by userfaultfd.

Link: https://lkml.kernel.org/r/20210603180546.9083-1-peterx@redhat.com
Fixes: f45ec5ff ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>	[5.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When hugetlb page fault (under overcommitting situation) and
memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following
race:

    CPU0:                           CPU1:

                                    gather_surplus_pages()
                                      page = alloc_surplus_huge_page()
    memory_failure_hugetlb()
      get_hwpoison_page(page)
        __get_hwpoison_page(page)
          get_page_unless_zero(page)
                                      zero = put_page_testzero(page)
                                      VM_BUG_ON_PAGE(!zero, page)
                                      enqueue_huge_page(h, page)
      put_page(page)

__get_hwpoison_page() only checks the page refcount before taking an
additional one for memory error handling, which is not enough because
there's a time window where compound pages have non-zero refcount during
hugetlb page initialization.

So make __get_hwpoison_page() check page status a bit more for hugetlb
pages with get_hwpoison_huge_page().  Checking hugetlb-specific flags
under hugetlb_lock makes sure that the hugetlb page is not transitive.
It's notable that another new function, HWPoisonHandlable(), is helpful
to prevent a race against other transitive page states (like a generic
compound page just before PageHuge becomes true).

Link: https://lkml.kernel.org/r/20210603233632.2964832-2-nao.horiguchi@gmail.com
Fixes: ead07f6a ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@vger.kernel.org>	[5.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 591a22c1 ("proc: Track /proc/$pid/attr/ opener mm_struct") we
started using __mem_open() to track the mm_struct at open-time, so that
we could then check it for writes.

But that also ended up making the permission checks at open time much
stricter - and not just for writes, but for reads too.  And that in turn
caused a regression for at least Fedora 29, where NIC interfaces fail to
start when using NetworkManager.

Since only the write side wanted the mm_struct test, ignore any failures
by __mem_open() at open time, leaving reads unaffected.  The write()
time verification of the mm_struct pointer will then catch the failure
case because a NULL pointer will not match a valid 'current->mm'.

Link: https://lore.kernel.org/netdev/YMjTlp2FSJYvoyFa@unreal/
Fixes: 591a22c1 ("proc: Track /proc/$pid/attr/ opener mm_struct")
Reported-and-tested-by: Leon Romanovsky <leon@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The proc_symlink() function returns NULL on error, it doesn't return
error pointers.

Fixes: 5b86d4ff ("afs: Implement network namespacing")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/YLjMRKX40pTrJvgf@mwanda/Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'perf-tools-fixes-for-v5.13-2021-06-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

Pull perf tools fixes from Arnaldo Carvalho de Melo:

 - Correct buffer copying when peeking events

 - Sync cpufeatures/disabled-features.h header with the kernel sources

* tag 'perf-tools-fixes-for-v5.13-2021-06-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
  tools headers cpufeatures: Sync with the kernel sources
  perf session: Correct buffer copying when peeking events

Pull NFS client bugfixes from Trond Myklebust:
 "Highlights include:

  Stable fixes:

   - Fix use-after-free in nfs4_init_client()

  Bugfixes:

   - Fix deadlock between nfs4_evict_inode() and nfs4_opendata_get_inode()

   - Fix second deadlock in nfs4_evict_inode()

   - nfs4_proc_set_acl should not change the value of NFS_CAP_UIDGID_NOMAP

   - Fix setting of the NFS_CAP_SECURITY_LABEL capability"

* tag 'nfs-for-5.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFSv4: Fix second deadlock in nfs4_evict_inode()
  NFSv4: Fix deadlock between nfs4_evict_inode() and nfs4_opendata_get_inode()
  NFS: FMODE_READ and friends are C macros, not enum types
  NFS: Fix a potential NULL dereference in nfs_get_client()
  NFS: Fix use-after-free in nfs4_init_client()
  NFS: Ensure the NFS_CAP_SECURITY_LABEL capability is set when appropriate
  NFSv4: nfs4_proc_set_acl needs to restore NFS_CAP_UIDGID_NOMAP on error.

Pull SCSI fixes from James Bottomley:
 "Four reasonably small fixes to the core for scsi host allocation
  failure paths.

  The root problem is that we're not freeing the memory allocated by
  dev_set_name(), which involves a rejig of may of the free on error
  paths to do put_device() instead of kfree which, in turn, has several
  other knock on ramifications and inspection turned up a few other
  lurking bugs"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: core: Only put parent device if host state differs from SHOST_CREATED
  scsi: core: Put .shost_dev in failure path if host state changes to RUNNING
  scsi: core: Fix failure handling of scsi_add_host_with_dma()
  scsi: core: Fix error handling of scsi_host_alloc()

Pull RISC-V fixes from Palmer Dabbelt:

 - A pair of XIP fixes: one to fix alternatives, and one to turn off the
   rest of the features that require code modification

 - A fix to a type that was causing some alternatives to break

 - A build fix for BUILTIN_DTB

* tag 'riscv-for-linus-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Fix BUILTIN_DTB for sifive and microchip soc
  riscv: alternative: fix typo in macro name
  riscv: code patching only works on !XIP_KERNEL
  riscv: xip: support runtime trap patching

0day robot reported a 9.2% regression for will-it-scale mmap1 test
case[1], caused by commit 57efa1fe ("mm/gup: prevent gup_fast from
racing with COW during fork").

Further debug shows the regression is due to that commit changes the
offset of hot fields 'mmap_lock' inside structure 'mm_struct', thus some
cache alignment changes.

From the perf data, the contention for 'mmap_lock' is very severe and
takes around 95% cpu cycles, and it is a rw_semaphore

        struct rw_semaphore {
                atomic_long_t count;	/* 8 bytes */
                atomic_long_t owner;	/* 8 bytes */
                struct optimistic_spin_queue osq; /* spinner MCS lock */
                ...

Before commit 57efa1fe adds the 'write_protect_seq', it happens to
have a very optimal cache alignment layout, as Linus explained:

 "and before the addition of the 'write_protect_seq' field, the
  mmap_sem was at offset 120 in 'struct mm_struct'.

  Which meant that count and owner were in two different cachelines,
  and then when you have contention and spend time in
  rwsem_down_write_slowpath(), this is probably *exactly* the kind
  of layout you want.

  Because first the rwsem_write_trylock() will do a cmpxchg on the
  first cacheline (for the optimistic fast-path), and then in the
  case of contention, rwsem_down_write_slowpath() will just access
  the second cacheline.

  Which is probably just optimal for a load that spends a lot of
  time contended - new waiters touch that first cacheline, and then
  they queue themselves up on the second cacheline."

After the commit, the rw_semaphore is at offset 128, which means the
'count' and 'owner' fields are now in the same cacheline, and causes
more cache bouncing.

Currently there are 3 "#ifdef CONFIG_XXX" before 'mmap_lock' which will
affect its offset:

  CONFIG_MMU
  CONFIG_MEMBARRIER
  CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES

The layout above is on 64 bits system with 0day's default kernel config
(similar to RHEL-8.3's config), in which all these 3 options are 'y'.
And the layout can vary with different kernel configs.

Relayouting a structure is usually a double-edged sword, as sometimes it
can helps one case, but hurt other cases.  For this case, one solution
is, as the newly added 'write_protect_seq' is a 4 bytes long seqcount_t
(when CONFIG_DEBUG_LOCK_ALLOC=n), placing it into an existing 4 bytes
hole in 'mm_struct' will not change other fields' alignment, while
restoring the regression.

Link: https://lore.kernel.org/lkml/20210525031636.GB7744@xsang-OptiPlex-9020/ [1]
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull USB fixes from Greg KH:
 "Here are a number of tiny USB fixes for 5.13-rc6.

  There are more than I would normally like, but there's been a bunch of
  people banging on the gadget and dwc3 and typec code recently for I
  think an Android release, which has resulted in a number of small
  fixes. It's nice to see companies send fixes upstream for this type of
  work, a notable change from years ago.

  Anyway, fixes in here are:

   - usb-serial device id updates

   - usb-serial cp210x driver fixes for broken firmware versions

   - typec fixes for crazy charging devices and other reported problems

   - dwc3 fixes for reported problems found

   - gadget fixes for reported problems

   - tiny xhci fixes

   - other small fixes for reported issues.

   - revert of a problem fix found by linux-next testing

  All of these have passed 0-day and linux-next testing with no reported
  problems (the revert for the found linux-next build problem included)"

* tag 'usb-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (44 commits)
  Revert "usb: gadget: fsl: Re-enable driver for ARM SoCs"
  usb: typec: mux: Fix copy-paste mistake in typec_mux_match
  usb: typec: ucsi: Clear PPM capability data in ucsi_init() error path
  usb: gadget: fsl: Re-enable driver for ARM SoCs
  usb: typec: wcove: Use LE to CPU conversion when accessing msg->header
  USB: serial: cp210x: fix CP2102N-A01 modem control
  USB: serial: cp210x: fix alternate function for CP2102N QFN20
  usb: misc: brcmstb-usb-pinmap: check return value after calling platform_get_resource()
  usb: dwc3: ep0: fix NULL pointer exception
  usb: gadget: eem: fix wrong eem header operation
  usb: typec: intel_pmc_mux: Put ACPI device using acpi_dev_put()
  usb: typec: intel_pmc_mux: Add missed error check for devm_ioremap_resource()
  usb: typec: intel_pmc_mux: Put fwnode in error case during ->probe()
  usb: typec: tcpm: Do not finish VDM AMS for retrying Responses
  usb: fix various gadget panics on 10gbps cabling
  usb: fix various gadgets null ptr deref on 10gbps cabling.
  usb: pci-quirks: disable D3cold on xhci suspend for s2idle on AMD Renoir
  usb: f_ncm: only first packet of aggregate needs to start timer
  USB: f_ncm: ncm_bitrate (speed) is unsigned
  MAINTAINERS: usb: add entry for isp1760
  ...

Pull serial driver fix from Greg KH:
 "A single 8250_exar serial driver fix for a reported problem with a
  change that happened in 5.13-rc1.

  It has been in linux-next with no reported problems"

* tag 'tty-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: 8250_exar: Avoid NULL pointer dereference at ->exit()

Pull staging driver fixes from Greg KH:
 "Two tiny staging driver fixes:

   - ralink-gdma driver authorship information fixed up

   - rtl8723bs driver fix for reported regression

  Both have been in linux-next for a while with no reported problems"

* tag 'staging-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: ralink-gdma: Remove incorrect author information
  staging: rtl8723bs: Fix uninitialized variables

Merge tag 'driver-core-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fix from Greg KH:
 "A single debugfs fix for 5.13-rc6, fixing a bug in
  debugfs_read_file_str() that showed up in 5.13-rc1.

  It has been in linux-next for a full week with no
  reported problems"

* tag 'driver-core-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  debugfs: Fix debugfs_read_file_str()

Pull char/misc driver fixes from Greg KH:
 "Here are some small misc driver fixes for 5.13-rc6 that fix some
  reported problems:

   - Tiny phy driver fixes for reported issues

   - rtsx regression for when the device suspended

   - mhi driver fix for a use-after-free

  All of these have been in linux-next for a few days with no reported
  issues"

* tag 'char-misc-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  misc: rtsx: separate aspm mode into MODE_REG and MODE_CFG
  bus: mhi: pci-generic: Fix hibernation
  bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove()
  bus: mhi: pci_generic: T99W175: update channel name from AT to DUN
  phy: Sparx5 Eth SerDes: check return value after calling platform_get_resource()
  phy: ralink: phy-mt7621-pci: drop 'of_match_ptr' to fix -Wunused-const-variable
  phy: ti: Fix an error code in wiz_probe()
  phy: phy-mtk-tphy: Fix some resource leaks in mtk_phy_init()
  phy: cadence: Sierra: Fix error return code in cdns_sierra_phy_probe()
  phy: usb: Fix misuse of IS_ENABLED

Pull pin control fixes from Linus Walleij:

 - Fix some documentation warnings for Allwinner

 - Fix duplicated GPIO groups on Qualcomm SDX55

 - Fix a double enablement bug in the Ralink driver

 - Fix the Qualcomm SC8180x Kconfig so the driver can be selected.

* tag 'pinctrl-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: qcom: Make it possible to select SC8180x TLMM
  pinctrl: ralink: rt2880: avoid to error in calls is pin is already enabled
  pinctrl: qcom: Fix duplication in gpio_groups
  pinctrl: aspeed: Fix minor documentation error

Pull block fixes from Jens Axboe:
 "A few fixes that should go into 5.13:

   - Fix a regression deadlock introduced in this release between open
     and remove of a bdev (Christoph)

   - Fix an async_xor md regression in this release (Xiao)

   - Fix bcache oversized read issue (Coly)"

* tag 'block-5.13-2021-06-12' of git://git.kernel.dk/linux-block:
  block: loop: fix deadlock between open and remove
  async_xor: check src_offs is not NULL before updating it
  bcache: avoid oversized read request in cache missing code path
  bcache: remove bcache device self-defined readahead

Pull io_uring fixes from Jens Axboe:
 "Just an API change for the registration changes that went into this
  release. Better to get it sorted out now than before it's too late"

* tag 'io_uring-5.13-2021-06-12' of git://git.kernel.dk/linux-block:
  io_uring: add feature flag for rsrc tags
  io_uring: change registration/upd/rsrc tagging ABI

Pull scheduler fixes from Ingo Molnar:
 "Misc fixes:

   - Fix performance regression caused by lack of intended batching of
     RCU callbacks by over-eager NOHZ-full code.

   - Fix cgroups related corruption of load_avg and load_sum metrics.

   - Three fixes to fix blocked load, util_sum/runnable_sum and util_est
     tracking bugs"

* tag 'sched-urgent-2021-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling
  sched/pelt: Ensure that *_sum is always synced with *_avg
  tick/nohz: Only check for RCU deferred wakeup on user/guest entry when needed
  sched/fair: Make sure to update tg contrib for blocked load
  sched/fair: Keep load_avg and load_sum synced

Pull perf fixes from Ingo Molnar:
 "Misc fixes:

   - Fix the NMI watchdog on ancient Intel CPUs

   - Remove a misguided, NMI-unsafe KASAN callback from the NMI-safe
     irq_work path used by perf.

   - Fix uncore events on Ice Lake servers.

   - Someone booted maxcpus=1 on an SNB-EP, and the uncore driver
     emitted warnings and was probably buggy. Fix it.

   - KCSAN found a genuine data race in the core perf code. Somewhat
     ironically the bug was introduced through a recent race fix. :-/
     In our defense, the new race window was much more narrow. Fix it"

* tag 'perf-urgent-2021-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/nmi_watchdog: Fix old-style NMI watchdog regression on old Intel CPUs
  irq_work: Make irq_work_queue() NMI-safe again
  perf/x86/intel/uncore: Fix M2M event umask for Ice Lake server
  perf/x86/intel/uncore: Fix a kernel WARNING triggered by maxcpus=1
  perf: Fix data race between pin_count increment/decrement

Pull objtool fixes from Ingo Molnar:
 "Two objtool fixes:

   - fix a bug that corrupts the code by mistakenly rewriting
     conditional jumps

   - fix another bug generating an incorrect ELF symbol table
     during retpoline rewriting"

* tag 'objtool-urgent-2021-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Only rewrite unconditional retpoline thunk calls
  objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()

Fix BUILTIN_DTB config which resulted in a dtb that was actually not
built into the Linux image: in the same manner as Canaan soc does,
create an object file from the dtb file that will get linked into the
Linux image.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

Pull tracing fixes from Steven Rostedt:

 - Fix the length check in the temp buffer filter

 - Fix build failure in bootconfig tools for "fallthrough" macro

 - Fix error return of bootconfig apply_xbc() routine

* tag 'trace-v5.13-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Correct the length check which causes memory corruption
  ftrace: Do not blindly read the ip address in ftrace_bug()
  tools/bootconfig: Fix a build error accroding to undefined fallthrough
  tools/bootconfig: Fix error return code in apply_xbc()

Pull clang LTO fix from Kees Cook:
 "Clang 13 fixed some IR behavior for LTO, but this broke work-arounds
  used in the kernel.

  Handle changes to needed LTO flags in Clang 13 (Tor Vic)"

* tag 'clang-features-v5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  x86, lto: Pass -stack-alignment only on LLD < 13.0.0

Pull gpio fix from Bartosz Golaszewski:
 "Fix a shift-out-of-bounds error in gpio-wcd934x"

* tag 'gpio-fixes-for-v5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
  gpio: wcd934x: Fix shift-out-of-bounds error

Pull drm fixes from Dave Airlie:
 "Another week of fixes, nothing too crazy, but a few all over the
  place.

  Two locking fixes in the core/ttm area, a couple of small driver fixes
  (radeon, sun4i, mcde, vc4). Then msm and amdgpu have a set of fixes
  each, mostly for smaller things, though the msm has a DSI fix for a
  black screen.

  I haven't seen any intel fixes this week so they may have a few that
  may or may not wait for next week.

  drm:
   - auth locking fix

  ttm:
   - locking fix

  amdgpu:
   - Use kvzmalloc in amdgu_bo_create
   - Use drm_dbg_kms for reporting failure to get a GEM FB
   - Fix some register offsets for Sienna Cichlid
   - Fix fall-through warning

  radeon:
   - memcpy_to/from_io fixes

  msm:
   - NULL ptr deref fix
   - CP_PROTECT reg programming fix
   - incorrect register shift fix
   - DSI blank screen fix

  sun4i:
   - hdmi output probing fix

  mcde:
   - DSI pipeline calc fix

  vc4:
   - out of bounds fix"

* tag 'drm-fixes-2021-06-11' of git://anongit.freedesktop.org/drm/drm:
  drm/msm/dsi: Stash away calculated vco frequency on recalc
  drm: Lock pointer access in drm_master_release()
  drm/mcde: Fix off by 10^3 in calculation
  drm/msm/a6xx: avoid shadow NULL reference in failure path
  drm/msm/a6xx: fix incorrectly set uavflagprd_inv field for A650
  drm/msm/a6xx: update/fix CP_PROTECT initialization
  radeon: use memcpy_to/fromio for UVD fw upload
  drm/amd/pm: Fix fall-through warning for Clang
  drm/amdgpu: Fix incorrect register offsets for Sienna Cichlid
  drm/amdgpu: Use drm_dbg_kms for reporting failure to get a GEM FB
  drm/amdgpu: switch kzalloc to kvzalloc in amdgpu_bo_create
  drm/msm: Init mm_list before accessing it for use_vram path
  drm: Fix use-after-free read in drm_getunique()
  drm/vc4: fix vc4_atomic_commit_tail() logic
  drm/ttm: fix deref of bo->ttm without holding the lock v2
  drm/sun4i: dw-hdmi: Make HDMI PHY into a platform device

Pull devicetree fix from Rob Herring:
 "A single fix for broken media/renesas,drif.yaml binding schema"

* tag 'devicetree-fixes-for-5.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  media: dt-bindings: media: renesas,drif: Fix fck definition

Pull MD related fix from Song.

* 'md-fixes' of https://git.kernel.org/pub/scm/linux/kernel/git/song/md:
  async_xor: check src_offs is not NULL before updating it

Pull ACPI fixes from Rafael Wysocki:
 "These revert a problematic recent commit and fix a regression
  introduced during the 5.12 development cycle.

  Specifics:

   - Revert recent commit that attempted to fix the FACS table reference
     counting but introduced a problem with accessing the hardware
     signature after hibernation (Zhang Rui).

   - Fix regression in the _OSC handling that broke the loading of ACPI
     tables on some systems (Mika Westerberg)"

* tag 'acpi-5.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: Pass the same capabilities to the _OSC regardless of the query flag
  Revert "ACPI: sleep: Put the FACS table after using it"