linux-stable.git/mm, branch v4.4.259

mm: hugetlb: fix a race between freeing and dissolving the page

2021-03-03T15:44:22+00:00

commit 7ffddd499ba6122b1a07828f023d1d67629aa017 upstream

There is a race condition between __free_huge_page()
and dissolve_free_huge_page().

  CPU0:                         CPU1:

  // page_count(page) == 1
  put_page(page)
    __free_huge_page(page)
                                dissolve_free_huge_page(page)
                                  spin_lock(&hugetlb_lock)
                                  // PageHuge(page) && !page_count(page)
                                  update_and_free_page(page)
                                  // page is freed to the buddy
                                  spin_unlock(&hugetlb_lock)
      spin_lock(&hugetlb_lock)
      clear_page_huge_active(page)
      enqueue_huge_page(page)
      // It is wrong, the page is already freed
      spin_unlock(&hugetlb_lock)

The race window is between put_page() and dissolve_free_huge_page().

We should make sure that the page is already on the free list when it is
dissolved.

As a result __free_huge_page would corrupt page(s) already in the buddy
allocator.

Link: https://lkml.kernel.org/r/20210115124942.46403-4-songmuchun@bytedance.com
Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Muchun Song 
Reviewed-by: Mike Kravetz 
Reviewed-by: Oscar Salvador 
Acked-by: Michal Hocko 
Cc: David Hildenbrand 
Cc: Yang Shi 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee 
Signed-off-by: Greg Kroah-Hartman

mm/hugetlb: fix potential double free in hugetlb_register_node() error path

2021-03-03T15:44:20+00:00

[ Upstream commit cc2205a67dec5a700227a693fc113441e73e4641 ]

In hugetlb_sysfs_add_hstate(), we would do kobject_put() on hstate_kobjs
when failed to create sysfs group but forget to set hstate_kobjs to NULL.
Then in hugetlb_register_node() error path, we may free it again via
hugetlb_unregister_node().

Link: https://lkml.kernel.org/r/20210107123249.36964-1-linmiaohe@huawei.com
Fixes: a3437870160c ("hugetlb: new sysfs interface")
Signed-off-by: Miaohe Lin 
Reviewed-by: Mike Kravetz 
Reviewed-by: Muchun Song 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/memory.c: fix potential pte_unmap_unlock pte error

2021-03-03T15:44:20+00:00

[ Upstream commit 90a3e375d324b2255b83e3dd29e99e2b05d82aaf ]

Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged
high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed,
we would break the loop with pte unchanged.  Then the wrong pte - 1 would
be passed to pte_unmap_unlock.

Andi said:

 "While the fix is correct, I'm not sure if it actually is a real bug.
  Is there any architecture that would do something else than unlocking
  the underlying page? If it's just the underlying page then it should
  be always the same page, so no bug"

Link: https://lkml.kernel.org/r/20210109080118.20885-1-linmiaohe@huawei.com
Fixes: 42e4089c789 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings")
Signed-off-by: Hongxiang Lou 
Signed-off-by: Miaohe Lin 
Cc: Thomas Gleixner 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: Josh Poimboeuf 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

memblock: do not start bottom-up allocations with kernel_end

2021-02-23T12:58:13+00:00

[ Upstream commit 2dcb3964544177c51853a210b6ad400de78ef17d ]

With kaslr the kernel image is placed at a random place, so starting the
bottom-up allocation with the kernel_end can result in an allocation
failure and a warning like this one:

  hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node
  ------------[ cut here ]------------
  memblock: bottom-up allocation failed, memory hotremove may be affected
  WARNING: CPU: 0 PID: 0 at mm/memblock.c:332 memblock_find_in_range_node+0x178/0x25a
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0+ #1169
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014
  RIP: 0010:memblock_find_in_range_node+0x178/0x25a
  Code: e9 6d ff ff ff 48 85 c0 0f 85 da 00 00 00 80 3d 9b 35 df 00 00 75 15 48 c7 c7 c0 75 59 88 c6 05 8b 35 df 00 01 e8 25 8a fa ff <0f> 0b 48 c7 44 24 20 ff ff ff ff 44 89 e6 44 89 ea 48 c7 c1 70 5c
  RSP: 0000:ffffffff88803d18 EFLAGS: 00010086 ORIG_RAX: 0000000000000000
  RAX: 0000000000000000 RBX: 0000000240000000 RCX: 00000000ffffdfff
  RDX: 00000000ffffdfff RSI: 00000000ffffffea RDI: 0000000000000046
  RBP: 0000000100000000 R08: ffffffff88922788 R09: 0000000000009ffb
  R10: 00000000ffffe000 R11: 3fffffffffffffff R12: 0000000000000000
  R13: 0000000000000000 R14: 0000000080000000 R15: 00000001fb42c000
  FS:  0000000000000000(0000) GS:ffffffff88f71000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffa080fb401000 CR3: 00000001fa80a000 CR4: 00000000000406b0
  Call Trace:
    memblock_alloc_range_nid+0x8d/0x11e
    cma_declare_contiguous_nid+0x2c4/0x38c
    hugetlb_cma_reserve+0xdc/0x128
    flush_tlb_one_kernel+0xc/0x20
    native_set_fixmap+0x82/0xd0
    flat_get_apic_id+0x5/0x10
    register_lapic_address+0x8e/0x97
    setup_arch+0x8a5/0xc3f
    start_kernel+0x66/0x547
    load_ucode_bsp+0x4c/0xcd
    secondary_startup_64_no_verify+0xb0/0xbb
  random: get_random_bytes called from __warn+0xab/0x110 with crng_init=0
  ---[ end trace f151227d0b39be70 ]---

At the same time, the kernel image is protected with memblock_reserve(),
so we can just start searching at PAGE_SIZE.  In this case the bottom-up
allocation has the same chances to success as a top-down allocation, so
there is no reason to fallback in the case of a failure.  All together it
simplifies the logic.

Link: https://lkml.kernel.org/r/20201217201214.3414100-2-guro@fb.com
Fixes: 8fabc623238e ("powerpc: Ensure that swiotlb buffer is allocated from low memory")
Signed-off-by: Roman Gushchin 
Reviewed-by: Mike Rapoport 
Cc: Joonsoo Kim 
Cc: Michal Hocko 
Cc: Rik van Riel 
Cc: Wonhyuk Yang 
Cc: Thiago Jung Bauermann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

memcg: fix a crash in wb_workfn when a device disappears

2021-02-23T12:58:12+00:00

[ Upstream commit 68f23b89067fdf187763e75a56087550624fdbee ]

Without memcg, there is a one-to-one mapping between the bdi and
bdi_writeback structures.  In this world, things are fairly
straightforward; the first thing bdi_unregister() does is to shutdown
the bdi_writeback structure (or wb), and part of that writeback ensures
that no other work queued against the wb, and that the wb is fully
drained.

With memcg, however, there is a one-to-many relationship between the bdi
and bdi_writeback structures; that is, there are multiple wb objects
which can all point to a single bdi.  There is a refcount which prevents
the bdi object from being released (and hence, unregistered).  So in
theory, the bdi_unregister() *should* only get called once its refcount
goes to zero (bdi_put will drop the refcount, and when it is zero,
release_bdi gets called, which calls bdi_unregister).

Unfortunately, del_gendisk() in block/gen_hd.c never got the memo about
the Brave New memcg World, and calls bdi_unregister directly.  It does
this without informing the file system, or the memcg code, or anything
else.  This causes the root wb associated with the bdi to be
unregistered, but none of the memcg-specific wb's are shutdown.  So when
one of these wb's are woken up to do delayed work, they try to
dereference their wb->bdi->dev to fetch the device name, but
unfortunately bdi->dev is now NULL, thanks to the bdi_unregister()
called by del_gendisk().  As a result, *boom*.

Fortunately, it looks like the rest of the writeback path is perfectly
happy with bdi->dev and bdi->owner being NULL, so the simplest fix is to
create a bdi_dev_name() function which can handle bdi->dev being NULL.
This also allows us to bulletproof the writeback tracepoints to prevent
them from dereferencing a NULL pointer and crashing the kernel if one is
tracing with memcg's enabled, and an iSCSI device dies or a USB storage
stick is pulled.

The most common way of triggering this will be hotremoval of a device
while writeback with memcg enabled is going on.  It was triggering
several times a day in a heavily loaded production environment.

Google Bug Id: 145475544

Link: https://lore.kernel.org/r/20191227194829.150110-1-tytso@mit.edu
Link: http://lkml.kernel.org/r/20191228005211.163952-1-tytso@mit.edu
Signed-off-by: Theodore Ts'o 
Cc: Chris Mason 
Cc: Tejun Heo 
Cc: Jens Axboe 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active

2021-02-10T08:07:28+00:00

commit ecbf4724e6061b4b01be20f6d797d64d462b2bc8 upstream.

The page_huge_active() can be called from scan_movable_pages() which do
not hold a reference count to the HugeTLB page.  So when we call
page_huge_active() from scan_movable_pages(), the HugeTLB page can be
freed parallel.  Then we will trigger a BUG_ON which is in the
page_huge_active() when CONFIG_DEBUG_VM is enabled.  Just remove the
VM_BUG_ON_PAGE.

Link: https://lkml.kernel.org/r/20210115124942.46403-6-songmuchun@bytedance.com
Fixes: 7e1f049efb86 ("mm: hugetlb: cleanup using paeg_huge_active()")
Signed-off-by: Muchun Song 
Reviewed-by: Mike Kravetz 
Acked-by: Michal Hocko 
Reviewed-by: Oscar Salvador 
Cc: David Hildenbrand 
Cc: Yang Shi 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: hugetlb: fix a race between isolating and freeing page

2021-02-10T08:07:28+00:00

commit 0eb2df2b5629794020f75e94655e1994af63f0d4 upstream.

There is a race between isolate_huge_page() and __free_huge_page().

  CPU0:                                     CPU1:

  if (PageHuge(page))
                                            put_page(page)
                                              __free_huge_page(page)
                                                  spin_lock(&hugetlb_lock)
                                                  update_and_free_page(page)
                                                    set_compound_page_dtor(page,
                                                      NULL_COMPOUND_DTOR)
                                                  spin_unlock(&hugetlb_lock)
    isolate_huge_page(page)
      // trigger BUG_ON
      VM_BUG_ON_PAGE(!PageHead(page), page)
      spin_lock(&hugetlb_lock)
      page_huge_active(page)
        // trigger BUG_ON
        VM_BUG_ON_PAGE(!PageHuge(page), page)
      spin_unlock(&hugetlb_lock)

When we isolate a HugeTLB page on CPU0.  Meanwhile, we free it to the
buddy allocator on CPU1.  Then, we can trigger a BUG_ON on CPU0, because
it is already freed to the buddy allocator.

Link: https://lkml.kernel.org/r/20210115124942.46403-5-songmuchun@bytedance.com
Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Muchun Song 
Reviewed-by: Mike Kravetz 
Acked-by: Michal Hocko 
Reviewed-by: Oscar Salvador 
Cc: David Hildenbrand 
Cc: Yang Shi 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: hugetlbfs: fix cannot migrate the fallocated HugeTLB page

2021-02-10T08:07:28+00:00

commit 585fc0d2871c9318c949fbf45b1f081edd489e96 upstream.

If a new hugetlb page is allocated during fallocate it will not be
marked as active (set_page_huge_active) which will result in a later
isolate_huge_page failure when the page migration code would like to
move that page.  Such a failure would be unexpected and wrong.

Only export set_page_huge_active, just leave clear_page_huge_active as
static.  Because there are no external users.

Link: https://lkml.kernel.org/r/20210115124942.46403-3-songmuchun@bytedance.com
Fixes: 70c3547e36f5 (hugetlbfs: add hugetlbfs_fallocate())
Signed-off-by: Muchun Song 
Acked-by: Michal Hocko 
Reviewed-by: Mike Kravetz 
Reviewed-by: Oscar Salvador 
Cc: David Hildenbrand 
Cc: Yang Shi 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Revert "mm/slub: fix a memory leak in sysfs_slab_add()"

2021-01-30T12:25:57+00:00

commit 757fed1d0898b893d7daa84183947c70f27632f3 upstream.

This reverts commit dde3c6b72a16c2db826f54b2d49bdea26c3534a2.

syzbot report a double-free bug. The following case can cause this bug.

 - mm/slab_common.c: create_cache(): if the __kmem_cache_create() fails,
   it does:

	out_free_cache:
		kmem_cache_free(kmem_cache, s);

 - but __kmem_cache_create() - at least for slub() - will have done

	sysfs_slab_add(s)
		-> sysfs_create_group() .. fails ..
		-> kobject_del(&s->kobj); .. which frees s ...

We can't remove the kmem_cache_free() in create_cache(), because other
error cases of __kmem_cache_create() do not free this.

So, revert the commit dde3c6b72a16 ("mm/slub: fix a memory leak in
sysfs_slab_add()") to fix this.

Reported-by: syzbot+d0bd96b4696c1ef67991@syzkaller.appspotmail.com
Fixes: dde3c6b72a16 ("mm/slub: fix a memory leak in sysfs_slab_add()")
Acked-by: Vlastimil Babka 
Signed-off-by: Wang Hai 
Cc: 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm, slub: consider rest of partial list if acquire_slab() fails

2021-01-23T14:36:55+00:00

commit 8ff60eb052eeba95cfb3efe16b08c9199f8121cf upstream.

acquire_slab() fails if there is contention on the freelist of the page
(probably because some other CPU is concurrently freeing an object from
the page).  In that case, it might make sense to look for a different page
(since there might be more remote frees to the page from other CPUs, and
we don't want contention on struct page).

However, the current code accidentally stops looking at the partial list
completely in that case.  Especially on kernels without CONFIG_NUMA set,
this means that get_partial() fails and new_slab_objects() falls back to
new_slab(), allocating new pages.  This could lead to an unnecessary
increase in memory fragmentation.

Link: https://lkml.kernel.org/r/20201228130853.1871516-1-jannh@google.com
Fixes: 7ced37197196 ("slub: Acquire_slab() avoid loop")
Signed-off-by: Jann Horn 
Acked-by: David Rientjes 
Acked-by: Joonsoo Kim 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman