linux-stable.git, branch v5.4.67

Linux 5.4.67

2020-09-23T10:40:47+00:00

Link: https://lore.kernel.org/lkml/20200921163121.870386357@linuxfoundation.org/
Tested-by: Linux Kernel Functional Testing 
Tested-by: Jon Hunter 
Tested-by: Guenter Roeck 
Signed-off-by: Greg Kroah-Hartman

dax: Fix compilation for CONFIG_DAX && !CONFIG_FS_DAX

2020-09-23T10:40:47+00:00

commit 88b67edd7247466bc47f01e1dc539b0d0d4b931e upstream.

dax_supported() is defined whenever CONFIG_DAX is enabled. So dummy
implementation should be defined only in !CONFIG_DAX case, not in
!CONFIG_FS_DAX case.

Fixes: e2ec51282545 ("dm: Call proper helper to determine dax support")
Cc: 
Reported-by: Geert Uytterhoeven 
Reported-by: Naresh Kamboju 
Reported-by: kernel test robot 
Signed-off-by: Jan Kara 
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

dm: Call proper helper to determine dax support

2020-09-23T10:40:47+00:00

commit e2ec5128254518cae320d5dc631b71b94160f663 upstream.

DM was calling generic_fsdax_supported() to determine whether a device
referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that
they don't have to duplicate common generic checks. High level code
should call dax_supported() helper which that calls into appropriate
helper for the particular device. This problem manifested itself as
kernel messages:

dm-3: error: dax access failed (-95)

when lvm2-testsuite run in cases where a DM device was stacked on top of
another DM device.

Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
Cc: 
Tested-by: Adrian Huang 
Signed-off-by: Jan Kara 
Acked-by: Mike Snitzer 
Reported-by: kernel test robot 
Link: https://lore.kernel.org/r/160061715195.13131.5503173247632041975.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

mm/memory_hotplug: drain per-cpu pages again during memory offline

2020-09-23T10:40:47+00:00

commit 9683182612214aa5f5e709fad49444b847cd866a upstream.

There is a race during page offline that can lead to infinite loop:
a page never ends up on a buddy list and __offline_pages() keeps
retrying infinitely or until a termination signal is received.

Thread#1 - a new process:

load_elf_binary
 begin_new_exec
  exec_mmap
   mmput
    exit_mmap
     tlb_finish_mmu
      tlb_flush_mmu
       release_pages
        free_unref_page_list
         free_unref_page_prepare
          set_pcppage_migratetype(page, migratetype);
             // Set page->index migration type below  MIGRATE_PCPTYPES

Thread#2 - hot-removes memory
__offline_pages
  start_isolate_page_range
    set_migratetype_isolate
      set_pageblock_migratetype(page, MIGRATE_ISOLATE);
        Set migration type to MIGRATE_ISOLATE-> set
        drain_all_pages(zone);
             // drain per-cpu page lists to buddy allocator.

Thread#1 - continue
         free_unref_page_commit
           migratetype = get_pcppage_migratetype(page);
              // get old migration type
           list_add(&page->lru, &pcp->lists[migratetype]);
              // add new page to already drained pcp list

Thread#2
Never drains pcp again, and therefore gets stuck in the loop.

The fix is to try to drain per-cpu lists again after
check_pages_isolated_cb() fails.

Fixes: c52e75935f8d ("mm: remove extra drain pages on pcp list")
Signed-off-by: Pavel Tatashin 
Signed-off-by: Andrew Morton 
Acked-by: David Rientjes 
Acked-by: Vlastimil Babka 
Acked-by: Michal Hocko 
Acked-by: David Hildenbrand 
Cc: Oscar Salvador 
Cc: Wei Yang 
Cc: 
Link: https://lkml.kernel.org/r/20200903140032.380431-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20200904151448.100489-2-pasha.tatashin@soleen.com
Link: http://lkml.kernel.org/r/20200904070235.GA15277@dhcp22.suse.cz
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

dm/dax: Fix table reference counts

2020-09-23T10:40:47+00:00

commit 02186d8897d49b0afd3c80b6cf23437d91024065 upstream.

A recent fix to the dm_dax_supported() flow uncovered a latent bug. When
dm_get_live_table() fails it is still required to drop the
srcu_read_lock(). Without this change the lvm2 test-suite triggers this
warning:

    # lvm2-testsuite --only pvmove-abort-all.sh

    WARNING: lock held when returning to user space!
    5.9.0-rc5+ #251 Tainted: G           OE
    ------------------------------------------------
    lvm/1318 is leaving the kernel with locks still held!
    1 lock held by lvm/1318:
     #0: ffff9372abb5a340 (&md->io_barrier){....}-{0:0}, at: dm_get_live_table+0x5/0xb0 [dm_mod]

...and later on this hang signature:

    INFO: task lvm:1344 blocked for more than 122 seconds.
          Tainted: G           OE     5.9.0-rc5+ #251
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    task:lvm             state:D stack:    0 pid: 1344 ppid:     1 flags:0x00004000
    Call Trace:
     __schedule+0x45f/0xa80
     ? finish_task_switch+0x249/0x2c0
     ? wait_for_completion+0x86/0x110
     schedule+0x5f/0xd0
     schedule_timeout+0x212/0x2a0
     ? __schedule+0x467/0xa80
     ? wait_for_completion+0x86/0x110
     wait_for_completion+0xb0/0x110
     __synchronize_srcu+0xd1/0x160
     ? __bpf_trace_rcu_utilization+0x10/0x10
     __dm_suspend+0x6d/0x210 [dm_mod]
     dm_suspend+0xf6/0x140 [dm_mod]

Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices")
Cc: 
Cc: Jan Kara 
Cc: Alasdair Kergon 
Cc: Mike Snitzer 
Reported-by: Adrian Huang 
Reviewed-by: Ira Weiny 
Tested-by: Adrian Huang 
Link: https://lore.kernel.org/r/160045867590.25663.7548541079217827340.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

selftests/vm: fix display of page size in map_hugetlb

2020-09-23T10:40:46+00:00

commit 1ec882fc81e3177faf055877310dbdb0c68eb7db upstream.

The displayed size is in bytes while the text says it is in kB.

Shift it by 10 to really display kBytes.

Fixes: fa7b9a805c79 ("tools/selftest/vm: allow choosing mem size and page size in map_hugetlb")
Signed-off-by: Christophe Leroy 
Signed-off-by: Andrew Morton 
Cc: 
Link: https://lkml.kernel.org/r/e27481224564a93d14106e750de31189deaa8bc8.1598861977.git.christophe.leroy@csgroup.eu
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

powerpc/dma: Fix dma_map_ops::get_required_mask

2020-09-23T10:40:46+00:00

commit 437ef802e0adc9f162a95213a3488e8646e5fc03 upstream.

There are 2 problems with it:
  1. "<" vs expected "<<"
  2. the shift number is an IOMMU page number mask, not an address
  mask as the IOMMU page shift is missing.

This did not hit us before f1565c24b596 ("powerpc: use the generic
dma_ops_bypass mode") because we had additional code to handle bypass
mask so this chunk (almost?) never executed.However there were
reports that aacraid does not work with "iommu=nobypass".

After f1565c24b596, aacraid (and probably others which call
dma_get_required_mask() before setting the mask) was unable to enable
64bit DMA and fall back to using IOMMU which was known not to work,
one of the problems is double free of an IOMMU page.

This fixes DMA for aacraid, both with and without "iommu=nobypass" in
the kernel command line. Verified with "stress-ng -d 4".

Fixes: 6a5c7be5e484 ("powerpc: Override dma_get_required_mask by platform hook and ops")
Cc: stable@vger.kernel.org # v3.2+
Signed-off-by: Alexey Kardashevskiy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200908015106.79661-1-aik@ozlabs.ru
Signed-off-by: Greg Kroah-Hartman

ehci-hcd: Move include to keep CRC stable

2020-09-23T10:40:46+00:00

commit 29231826f3bd65500118c473fccf31c0cf14dbc0 upstream.

The CRC calculation done by genksyms is triggered when the parser hits
EXPORT_SYMBOL*() macros. At this point, genksyms recursively expands the
types of the function parameters, and uses that as the input for the CRC
calculation. In the case of forward-declared structs, the type expands
to 'UNKNOWN'. Following this, it appears that the result of the
expansion of each type is cached somewhere, and seems to be re-used
when/if the same type is seen again for another exported symbol in the
same C file.

Unfortunately, this can cause CRC 'stability' issues when a struct
definition becomes visible in the middle of a C file. For example, let's
assume code with the following pattern:

    struct foo;

    int bar(struct foo *arg)
    {
	/* Do work ... */
    }
    EXPORT_SYMBOL_GPL(bar);

    /* This contains struct foo's definition */
    #include "foo.h"

    int baz(struct foo *arg)
    {
	/* Do more work ... */
    }
    EXPORT_SYMBOL_GPL(baz);

Here, baz's CRC will be computed using the expansion of struct foo that
was cached after bar's CRC calculation ('UNKOWN' here). But if
EXPORT_SYMBOL_GPL(bar) is removed from the file (because of e.g. symbol
trimming using CONFIG_TRIM_UNUSED_KSYMS), struct foo will be expanded
late, during baz's CRC calculation, which now has visibility over the
full struct definition, hence resulting in a different CRC for baz.

The proper fix for this certainly is in genksyms, but that will take me
some time to get right. In the meantime, we have seen one occurrence of
this in the ehci-hcd code which hits this problem because of the way it
includes C files halfway through the code together with an unlucky mix
of symbol trimming.

In order to workaround this, move the include done in ehci-hub.c early
in ehci-hcd.c, hence making sure the struct definitions are visible to
the entire file. This improves CRC stability of the ehci-hcd exports
even when symbol trimming is enabled.

Acked-by: Alan Stern 
Cc: stable 
Signed-off-by: Quentin Perret 
Link: https://lore.kernel.org/r/20200916171825.3228122-1-qperret@google.com
Signed-off-by: Greg Kroah-Hartman

s390/zcrypt: fix kmalloc 256k failure

2020-09-23T10:40:46+00:00

commit b6186d7fb53349efd274263a45f0b08749ccaa2d upstream.

Tests showed that under stress conditions the kernel may
temporary fail to allocate 256k with kmalloc. However,
this fix reworks the related code in the cca_findcard2()
function to use kvmalloc instead.

Signed-off-by: Harald Freudenberger 
Reviewed-by: Ingo Franzki 
Cc: Stable 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

x86/boot/compressed: Disable relocation relaxation

2020-09-23T10:40:46+00:00

commit 09e43968db40c33a73e9ddbfd937f46d5c334924 upstream.

The x86-64 psABI [0] specifies special relocation types
(R_X86_64_[REX_]GOTPCRELX) for indirection through the Global Offset
Table, semantically equivalent to R_X86_64_GOTPCREL, which the linker
can take advantage of for optimization (relaxation) at link time. This
is supported by LLD and binutils versions 2.26 onwards.

The compressed kernel is position-independent code, however, when using
LLD or binutils versions before 2.27, it must be linked without the -pie
option. In this case, the linker may optimize certain instructions into
a non-position-independent form, by converting foo@GOTPCREL(%rip) to $foo.

This potential issue has been present with LLD and binutils-2.26 for a
long time, but it has never manifested itself before now:

- LLD and binutils-2.26 only relax
	movq	foo@GOTPCREL(%rip), %reg
  to
	leaq	foo(%rip), %reg
  which is still position-independent, rather than
	mov	$foo, %reg
  which is permitted by the psABI when -pie is not enabled.

- GCC happens to only generate GOTPCREL relocations on mov instructions.

- CLang does generate GOTPCREL relocations on non-mov instructions, but
  when building the compressed kernel, it uses its integrated assembler
  (due to the redefinition of KBUILD_CFLAGS dropping -no-integrated-as),
  which has so far defaulted to not generating the GOTPCRELX
  relocations.

Nick Desaulniers reports [1,2]:

  "A recent change [3] to a default value of configuration variable
   (ENABLE_X86_RELAX_RELOCATIONS OFF -> ON) in LLVM now causes Clang's
   integrated assembler to emit R_X86_64_GOTPCRELX/R_X86_64_REX_GOTPCRELX
   relocations. LLD will relax instructions with these relocations based
   on whether the image is being linked as position independent or not.
   When not, then LLD will relax these instructions to use absolute
   addressing mode (R_RELAX_GOT_PC_NOPIC). This causes kernels built with
   Clang and linked with LLD to fail to boot."

Patch series [4] is a solution to allow the compressed kernel to be
linked with -pie unconditionally, but even if merged is unlikely to be
backported. As a simple solution that can be applied to stable as well,
prevent the assembler from generating the relaxed relocation types using
the -mrelax-relocations=no option. For ease of backporting, do this
unconditionally.

[0] https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/linker-optimization.tex#L65
[1] https://lore.kernel.org/lkml/20200807194100.3570838-1-ndesaulniers@google.com/
[2] https://github.com/ClangBuiltLinux/linux/issues/1121
[3] https://reviews.llvm.org/rGc41a18cf61790fc898dcda1055c3efbf442c14c0
[4] https://lore.kernel.org/lkml/20200731202738.2577854-1-nivedita@alum.mit.edu/

Reported-by: Nick Desaulniers 
Signed-off-by: Arvind Sankar 
Signed-off-by: Ingo Molnar 
Tested-by: Nick Desaulniers 
Tested-by: Sedat Dilek 
Acked-by: Ard Biesheuvel 
Reviewed-by: Nick Desaulniers 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200812004308.1448603-1-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman