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  1. 25 Jul, 2018 2 commits
    • Johannes Weiner's avatar
      arm64: fix vmemmap BUILD_BUG_ON() triggering on !vmemmap setups · 7b0eb6b4
      Johannes Weiner authored 
      Arnd reports the following arm64 randconfig build error with the PSI
patches that add another page flag:

  /git/arm-soc/arch/arm64/mm/init.c: In function 'mem_init':
  /git/arm-soc/include/linux/compiler.h:357:38: error: call to
  '__compiletime_assert_618' declared with attribute error: BUILD_BUG_ON
  failed: sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT)

The additional page flag causes other information stored in
page->flags to get bumped into their own struct page member:

  #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <=
  BITS_PER_LONG - NR_PAGEFLAGS
  #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
  #else
  #define LAST_CPUPID_WIDTH 0
  #endif

  #if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
  #define LAST_CPUPID_NOT_IN_PAGE_FLAGS
  #endif

which in turn causes the struct page size to exceed the size set in
STRUCT_PAGE_MAX_SHIFT. This value is an an estimate used to size the
VMEMMAP page array according to address space and struct page size.

However, the check is performed - and triggers here - on a !VMEMMAP
config, which consumes an additional 22 page bits for the sparse
section id. When VMEMMAP is enabled, those bits are returned, cpupid
doesn't need its own member, and the page passes the VMEMMAP check.

Restrict that check to the situation it was meant to check: that we
are sizing the VMEMMAP page array correctly.

Says Arnd:

    Further experiments show that the build error already existed before,
    but was only triggered with larger values of CONFIG_NR_CPU and/or
    CONFIG_NODES_SHIFT that might be used in actual configurations but
    not in randconfig builds.

    With longer CPU and node masks, I could recreate the problem with
    kernels as old as linux-4.7 when arm64 NUMA support got added.
Reported-by: default avatarArnd Bergmann <arnd@arndb.de>
Tested-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org
Fixes: 1a2db300 ("arm64, numa: Add NUMA support for arm64 platforms.")
Fixes: 3e1907d5 ("arm64: mm: move vmemmap region right below the linear region")
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      7b0eb6b4
    • Dirk Mueller's avatar
      arm64: Check for errata before evaluating cpu features · dc0e3658
      Dirk Mueller authored 
      Since commit d3aec8a2 ("arm64: capabilities: Restrict KPTI
detection to boot-time CPUs") we rely on errata flags being already
populated during feature enumeration. The order of errata and
features was flipped as part of commit ed478b3f ("arm64:
capabilities: Group handling of features and errata workarounds").

Return to the orginal order of errata and feature evaluation to
ensure errata flags are present during feature evaluation.

Fixes: ed478b3f ("arm64: capabilities: Group handling of
    features and errata workarounds")
CC: Suzuki K Poulose <suzuki.poulose@arm.com>
CC: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarDirk Mueller <dmueller@suse.com>
Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      dc0e3658
  3. 22 Jul, 2018 8 commits
  5. 21 Jul, 2018 12 commits
  7. 20 Jul, 2018 17 commits
  9. 19 Jul, 2018 1 commit
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