linux-stable.git/mm, branch v5.4.185

memfd: fix F_SEAL_WRITE after shmem huge page allocated

2022-03-08T18:07:49+00:00

commit f2b277c4d1c63a85127e8aa2588e9cc3bd21cb99 upstream.

Wangyong reports: after enabling tmpfs filesystem to support transparent
hugepage with the following command:

  echo always > /sys/kernel/mm/transparent_hugepage/shmem_enabled

the docker program tries to add F_SEAL_WRITE through the following
command, but it fails unexpectedly with errno EBUSY:

  fcntl(5, F_ADD_SEALS, F_SEAL_WRITE) = -1.

That is because memfd_tag_pins() and memfd_wait_for_pins() were never
updated for shmem huge pages: checking page_mapcount() against
page_count() is hopeless on THP subpages - they need to check
total_mapcount() against page_count() on THP heads only.

Make memfd_tag_pins() (compared > 1) as strict as memfd_wait_for_pins()
(compared != 1): either can be justified, but given the non-atomic
total_mapcount() calculation, it is better now to be strict.  Bear in
mind that total_mapcount() itself scans all of the THP subpages, when
choosing to take an XA_CHECK_SCHED latency break.

Also fix the unlikely xa_is_value() case in memfd_wait_for_pins(): if a
page has been swapped out since memfd_tag_pins(), then its refcount must
have fallen, and so it can safely be untagged.

Link: https://lkml.kernel.org/r/a4f79248-df75-2c8c-3df-ba3317ccb5da@google.com
Signed-off-by: Hugh Dickins 
Reported-by: Zeal Robot 
Reported-by: wangyong 
Cc: Mike Kravetz 
Cc: Matthew Wilcox (Oracle) 
Cc: CGEL ZTE 
Cc: Kirill A. Shutemov 
Cc: Song Liu 
Cc: Yang Yang 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

memblock: use kfree() to release kmalloced memblock regions

2022-03-02T10:41:18+00:00

commit c94afc46cae7ad41b2ad6a99368147879f4b0e56 upstream.

memblock.{reserved,memory}.regions may be allocated using kmalloc() in
memblock_double_array(). Use kfree() to release these kmalloced regions
indicated by memblock_{reserved,memory}_in_slab.

Signed-off-by: Miaohe Lin 
Fixes: 3010f876500f ("mm: discard memblock data later")
Signed-off-by: Mike Rapoport 
Signed-off-by: Greg Kroah-Hartman

mm/kmemleak: avoid scanning potential huge holes

2022-02-08T17:24:28+00:00

commit c10a0f877fe007021d70f9cada240f42adc2b5db upstream.

When using devm_request_free_mem_region() and devm_memremap_pages() to
add ZONE_DEVICE memory, if requested free mem region's end pfn were
huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see
move_pfn_range_to_zone()).  Thus it creates a huge hole between
node_start_pfn() and node_end_pfn().

We found on some AMD APUs, amdkfd requested such a free mem region and
created a huge hole.  In such a case, following code snippet was just
doing busy test_bit() looping on the huge hole.

  for (pfn = start_pfn; pfn < end_pfn; pfn++) {
	struct page *page = pfn_to_online_page(pfn);
		if (!page)
			continue;
	...
  }

So we got a soft lockup:

  watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221]
  CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1
  RIP: 0010:pfn_to_online_page+0x5/0xd0
  Call Trace:
    ? kmemleak_scan+0x16a/0x440
    kmemleak_write+0x306/0x3a0
    ? common_file_perm+0x72/0x170
    full_proxy_write+0x5c/0x90
    vfs_write+0xb9/0x260
    ksys_write+0x67/0xe0
    __x64_sys_write+0x1a/0x20
    do_syscall_64+0x3b/0xc0
    entry_SYSCALL_64_after_hwframe+0x44/0xae

I did some tests with the patch.

(1) amdgpu module unloaded

before the patch:

  real    0m0.976s
  user    0m0.000s
  sys     0m0.968s

after the patch:

  real    0m0.981s
  user    0m0.000s
  sys     0m0.973s

(2) amdgpu module loaded

before the patch:

  real    0m35.365s
  user    0m0.000s
  sys     0m35.354s

after the patch:

  real    0m1.049s
  user    0m0.000s
  sys     0m1.042s

Link: https://lkml.kernel.org/r/20211108140029.721144-1-lang.yu@amd.com
Signed-off-by: Lang Yu 
Acked-by: David Hildenbrand 
Acked-by: Catalin Marinas 
Cc: Oscar Salvador 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode

2022-01-27T08:19:29+00:00

commit 62c9827cbb996c2c04f615ecd783ce28bcea894b upstream.

Fix a data race in commit 779750d20b93 ("shmem: split huge pages beyond
i_size under memory pressure").

Here are call traces causing race:

   Call Trace 1:
     shmem_unused_huge_shrink+0x3ae/0x410
     ? __list_lru_walk_one.isra.5+0x33/0x160
     super_cache_scan+0x17c/0x190
     shrink_slab.part.55+0x1ef/0x3f0
     shrink_node+0x10e/0x330
     kswapd+0x380/0x740
     kthread+0xfc/0x130
     ? mem_cgroup_shrink_node+0x170/0x170
     ? kthread_create_on_node+0x70/0x70
     ret_from_fork+0x1f/0x30

   Call Trace 2:
     shmem_evict_inode+0xd8/0x190
     evict+0xbe/0x1c0
     do_unlinkat+0x137/0x330
     do_syscall_64+0x76/0x120
     entry_SYSCALL_64_after_hwframe+0x3d/0xa2

A simple explanation:

Image there are 3 items in the local list (@list).  In the first
traversal, A is not deleted from @list.

  1)    A->B->C
        ^
        |
        pos (leave)

In the second traversal, B is deleted from @list.  Concurrently, A is
deleted from @list through shmem_evict_inode() since last reference
counter of inode is dropped by other thread.  Then the @list is corrupted.

  2)    A->B->C
        ^  ^
        |  |
     evict pos (drop)

We should make sure the inode is either on the global list or deleted from
any local list before iput().

Fixed by moving inodes back to global list before we put them.

[akpm@linux-foundation.org: coding style fixes]

Link: https://lkml.kernel.org/r/20211125064502.99983-1-ligang.bdlg@bytedance.com
Fixes: 779750d20b93 ("shmem: split huge pages beyond i_size under memory pressure")
Signed-off-by: Gang Li 
Reviewed-by: Muchun Song 
Acked-by: Kirill A. Shutemov 
Cc: Hugh Dickins 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm/page_alloc.c: do not warn allocation failure on zone DMA if no managed pages

2022-01-27T08:19:28+00:00

commit c4dc63f0032c77464fbd4e7a6afc22fa6913c4a7 upstream.

In kdump kernel of x86_64, page allocation failure is observed:

 kworker/u2:2: page allocation failure: order:0, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
 CPU: 0 PID: 55 Comm: kworker/u2:2 Not tainted 5.16.0-rc4+ #5
 Hardware name: AMD Dinar/Dinar, BIOS RDN1505B 06/05/2013
 Workqueue: events_unbound async_run_entry_fn
 Call Trace:
  
  dump_stack_lvl+0x48/0x5e
  warn_alloc.cold+0x72/0xd6
  __alloc_pages_slowpath.constprop.0+0xc69/0xcd0
  __alloc_pages+0x1df/0x210
  new_slab+0x389/0x4d0
  ___slab_alloc+0x58f/0x770
  __slab_alloc.constprop.0+0x4a/0x80
  kmem_cache_alloc_trace+0x24b/0x2c0
  sr_probe+0x1db/0x620
  ......
  device_add+0x405/0x920
  ......
  __scsi_add_device+0xe5/0x100
  ata_scsi_scan_host+0x97/0x1d0
  async_run_entry_fn+0x30/0x130
  process_one_work+0x1e8/0x3c0
  worker_thread+0x50/0x3b0
  ? rescuer_thread+0x350/0x350
  kthread+0x16b/0x190
  ? set_kthread_struct+0x40/0x40
  ret_from_fork+0x22/0x30
  
 Mem-Info:
 ......

The above failure happened when calling kmalloc() to allocate buffer with
GFP_DMA.  It requests to allocate slab page from DMA zone while no managed
pages at all in there.

 sr_probe()
 --> get_capabilities()
     --> buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);

Because in the current kernel, dma-kmalloc will be created as long as
CONFIG_ZONE_DMA is enabled.  However, kdump kernel of x86_64 doesn't have
managed pages on DMA zone since commit 6f599d84231f ("x86/kdump: Always
reserve the low 1M when the crashkernel option is specified").  The
failure can be always reproduced.

For now, let's mute the warning of allocation failure if requesting pages
from DMA zone while no managed pages.

[akpm@linux-foundation.org: fix warning]

Link: https://lkml.kernel.org/r/20211223094435.248523-4-bhe@redhat.com
Fixes: 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
Signed-off-by: Baoquan He 
Acked-by: John Donnelly  
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Cc: Vlastimil Babka 
Cc: Borislav Petkov 
Cc: Christoph Hellwig 
Cc: David Hildenbrand 
Cc: David Laight 
Cc: Marek Szyprowski 
Cc: Robin Murphy 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm_zone: add function to check if managed dma zone exists

2022-01-27T08:19:28+00:00

commit 62b3107073646e0946bd97ff926832bafb846d17 upstream.

Patch series "Handle warning of allocation failure on DMA zone w/o
managed pages", v4.

**Problem observed:
On x86_64, when crash is triggered and entering into kdump kernel, page
allocation failure can always be seen.

 ---------------------------------
 DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
 swapper/0: page allocation failure: order:5, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
 CPU: 0 PID: 1 Comm: swapper/0
 Call Trace:
  dump_stack+0x7f/0xa1
  warn_alloc.cold+0x72/0xd6
  ......
  __alloc_pages+0x24d/0x2c0
  ......
  dma_atomic_pool_init+0xdb/0x176
  do_one_initcall+0x67/0x320
  ? rcu_read_lock_sched_held+0x3f/0x80
  kernel_init_freeable+0x290/0x2dc
  ? rest_init+0x24f/0x24f
  kernel_init+0xa/0x111
  ret_from_fork+0x22/0x30
 Mem-Info:
 ------------------------------------

***Root cause:
In the current kernel, it assumes that DMA zone must have managed pages
and try to request pages if CONFIG_ZONE_DMA is enabled. While this is not
always true. E.g in kdump kernel of x86_64, only low 1M is presented and
locked down at very early stage of boot, so that this low 1M won't be
added into buddy allocator to become managed pages of DMA zone. This
exception will always cause page allocation failure if page is requested
from DMA zone.

***Investigation:
This failure happens since below commit merged into linus's tree.
  1a6a9044b967 x86/setup: Remove CONFIG_X86_RESERVE_LOW and reservelow= options
  23721c8e92f7 x86/crash: Remove crash_reserve_low_1M()
  f1d4d47c5851 x86/setup: Always reserve the first 1M of RAM
  7c321eb2b843 x86/kdump: Remove the backup region handling
  6f599d84231f x86/kdump: Always reserve the low 1M when the crashkernel option is specified

Before them, on x86_64, the low 640K area will be reused by kdump kernel.
So in kdump kernel, the content of low 640K area is copied into a backup
region for dumping before jumping into kdump. Then except of those firmware
reserved region in [0, 640K], the left area will be added into buddy
allocator to become available managed pages of DMA zone.

However, after above commits applied, in kdump kernel of x86_64, the low
1M is reserved by memblock, but not released to buddy allocator. So any
later page allocation requested from DMA zone will fail.

At the beginning, if crashkernel is reserved, the low 1M need be locked
down because AMD SME encrypts memory making the old backup region
mechanims impossible when switching into kdump kernel.

Later, it was also observed that there are BIOSes corrupting memory
under 1M. To solve this, in commit f1d4d47c5851, the entire region of
low 1M is always reserved after the real mode trampoline is allocated.

Besides, recently, Intel engineer mentioned their TDX (Trusted domain
extensions) which is under development in kernel also needs to lock down
the low 1M. So we can't simply revert above commits to fix the page allocation
failure from DMA zone as someone suggested.

***Solution:
Currently, only DMA atomic pool and dma-kmalloc will initialize and
request page allocation with GFP_DMA during bootup.

So only initializ DMA atomic pool when DMA zone has available managed
pages, otherwise just skip the initialization.

For dma-kmalloc(), for the time being, let's mute the warning of
allocation failure if requesting pages from DMA zone while no manged
pages.  Meanwhile, change code to use dma_alloc_xx/dma_map_xx API to
replace kmalloc(GFP_DMA), or do not use GFP_DMA when calling kmalloc() if
not necessary.  Christoph is posting patches to fix those under
drivers/scsi/.  Finally, we can remove the need of dma-kmalloc() as people
suggested.

This patch (of 3):

In some places of the current kernel, it assumes that dma zone must have
managed pages if CONFIG_ZONE_DMA is enabled.  While this is not always
true.  E.g in kdump kernel of x86_64, only low 1M is presented and locked
down at very early stage of boot, so that there's no managed pages at all
in DMA zone.  This exception will always cause page allocation failure if
page is requested from DMA zone.

Here add function has_managed_dma() and the relevant helper functions to
check if there's DMA zone with managed pages.  It will be used in later
patches.

Link: https://lkml.kernel.org/r/20211223094435.248523-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20211223094435.248523-2-bhe@redhat.com
Fixes: 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
Signed-off-by: Baoquan He 
Reviewed-by: David Hildenbrand 
Acked-by: John Donnelly  
Cc: Christoph Hellwig 
Cc: Christoph Lameter 
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Cc: Vlastimil Babka 
Cc: David Laight 
Cc: Borislav Petkov 
Cc: Marek Szyprowski 
Cc: Robin Murphy 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: mempolicy: fix THP allocations escaping mempolicy restrictions

2021-12-29T11:23:37+00:00

commit 338635340669d5b317c7e8dcf4fff4a0f3651d87 upstream.

alloc_pages_vma() may try to allocate THP page on the local NUMA node
first:

	page = __alloc_pages_node(hpage_node,
		gfp | __GFP_THISNODE | __GFP_NORETRY, order);

And if the allocation fails it retries allowing remote memory:

	if (!page && (gfp & __GFP_DIRECT_RECLAIM))
    		page = __alloc_pages_node(hpage_node,
					gfp, order);

However, this retry allocation completely ignores memory policy nodemask
allowing allocation to escape restrictions.

The first appearance of this bug seems to be the commit ac5b2c18911f
("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings").

The bug disappeared later in the commit 89c83fb539f9 ("mm, thp:
consolidate THP gfp handling into alloc_hugepage_direct_gfpmask") and
reappeared again in slightly different form in the commit 76e654cc91bb
("mm, page_alloc: allow hugepage fallback to remote nodes when
madvised")

Fix this by passing correct nodemask to the __alloc_pages() call.

The demonstration/reproducer of the problem:

    $ mount -oremount,size=4G,huge=always /dev/shm/
    $ echo always > /sys/kernel/mm/transparent_hugepage/defrag
    $ cat mbind_thp.c
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 

    #define SIZE 2ULL << 30
    int main(int argc, char **argv)
    {
        int fd;
        unsigned long long i;
        char *addr;
        pid_t pid;
        char buf[100];
        unsigned long nodemask = 1;

        fd = open("/dev/shm/test", O_RDWR|O_CREAT);
        assert(fd > 0);
        assert(ftruncate(fd, SIZE) == 0);

        addr = mmap(NULL, SIZE, PROT_READ|PROT_WRITE,
                           MAP_SHARED, fd, 0);

        assert(mbind(addr, SIZE, MPOL_BIND, &nodemask, 2, MPOL_MF_STRICT|MPOL_MF_MOVE)==0);
        for (i = 0; i < SIZE; i+=4096) {
          addr[i] = 1;
        }
        pid = getpid();
        snprintf(buf, sizeof(buf), "grep shm /proc/%d/numa_maps", pid);
        system(buf);
        sleep(10000);

        return 0;
    }
    $ gcc mbind_thp.c -o mbind_thp -lnuma
    $ numactl -H
    available: 2 nodes (0-1)
    node 0 cpus: 0 2
    node 0 size: 1918 MB
    node 0 free: 1595 MB
    node 1 cpus: 1 3
    node 1 size: 2014 MB
    node 1 free: 1731 MB
    node distances:
    node   0   1
      0:  10  20
      1:  20  10
    $ rm -f /dev/shm/test; taskset -c 0 ./mbind_thp
    7fd970a00000 bind:0 file=/dev/shm/test dirty=524288 active=0 N0=396800 N1=127488 kernelpagesize_kB=4

Link: https://lkml.kernel.org/r/20211208165343.22349-1-arbn@yandex-team.com
Fixes: ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings")
Signed-off-by: Andrey Ryabinin 
Acked-by: Michal Hocko 
Acked-by: Mel Gorman 
Acked-by: David Rientjes 
Cc: Andrea Arcangeli 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

memblock: ensure there is no overflow in memblock_overlaps_region()

2021-12-17T09:12:24+00:00

commit 023accf5cdc1e504a9b04187ec23ff156fe53d90 upstream.

There maybe an overflow in memblock_overlaps_region() if it is called with
base and size such that

	base + size > PHYS_ADDR_MAX

Make sure that memblock_overlaps_region() caps the size to prevent such
overflow and remove now duplicated call to memblock_cap_size() from
memblock_is_region_reserved().

Signed-off-by: Mike Rapoport 
Tested-by: Tony Lindgren 
Link: https://lore.kernel.org/lkml/20210630071211.21011-1-rppt@kernel.org/
Signed-off-by: Mark-PK Tsai 
Signed-off-by: Greg Kroah-Hartman

mm: bdi: initialize bdi_min_ratio when bdi is unregistered

2021-12-14T13:49:00+00:00

commit 3c376dfafbf7a8ea0dea212d095ddd83e93280bb upstream.

Initialize min_ratio if it is set during bdi unregistration.  This can
prevent problems that may occur a when bdi is removed without resetting
min_ratio.

For example.
1) insert external sdcard
2) set external sdcard's min_ratio 70
3) remove external sdcard without setting min_ratio 0
4) insert external sdcard
5) set external sdcard's min_ratio 70 << error occur(can't set)

Because when an sdcard is removed, the present bdi_min_ratio value will
remain.  Currently, the only way to reset bdi_min_ratio is to reboot.

[akpm@linux-foundation.org: tweak comment and coding style]

Link: https://lkml.kernel.org/r/20211021161942.5983-1-mj0123.lee@samsung.com
Signed-off-by: Manjong Lee 
Acked-by: Peter Zijlstra (Intel) 
Cc: Changheun Lee 
Cc: Jens Axboe 
Cc: Christoph Hellwig 
Cc: Matthew Wilcox 
Cc: 
Cc: 
Cc: 
Cc: 
Cc: 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

hugetlbfs: flush TLBs correctly after huge_pmd_unshare

2021-11-26T09:47:23+00:00

commit a4a118f2eead1d6c49e00765de89878288d4b890 upstream.

When __unmap_hugepage_range() calls to huge_pmd_unshare() succeed, a TLB
flush is missing.  This TLB flush must be performed before releasing the
i_mmap_rwsem, in order to prevent an unshared PMDs page from being
released and reused before the TLB flush took place.

Arguably, a comprehensive solution would use mmu_gather interface to
batch the TLB flushes and the PMDs page release, however it is not an
easy solution: (1) try_to_unmap_one() and try_to_migrate_one() also call
huge_pmd_unshare() and they cannot use the mmu_gather interface; and (2)
deferring the release of the page reference for the PMDs page until
after i_mmap_rwsem is dropeed can confuse huge_pmd_unshare() into
thinking PMDs are shared when they are not.

Fix __unmap_hugepage_range() by adding the missing TLB flush, and
forcing a flush when unshare is successful.

Fixes: 24669e58477e ("hugetlb: use mmu_gather instead of a temporary linked list for accumulating pages)" # 3.6
Signed-off-by: Nadav Amit 
Reviewed-by: Mike Kravetz 
Cc: Aneesh Kumar K.V 
Cc: KAMEZAWA Hiroyuki 
Cc: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman