1. 12 Jan, 2020 37 commits
  2. 09 Jan, 2020 3 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.19.94 · cb1f9a16
      Greg Kroah-Hartman authored
      cb1f9a16
    • Alexander Shishkin's avatar
      perf/x86/intel/bts: Fix the use of page_private() · 78880475
      Alexander Shishkin authored
      [ Upstream commit ff61541c ]
      
      Commit
      
        8062382c ("perf/x86/intel/bts: Add BTS PMU driver")
      
      brought in a warning with the BTS buffer initialization
      that is easily tripped with (assuming KPTI is disabled):
      
      instantly throwing:
      
      > ------------[ cut here ]------------
      > WARNING: CPU: 2 PID: 326 at arch/x86/events/intel/bts.c:86 bts_buffer_setup_aux+0x117/0x3d0
      > Modules linked in:
      > CPU: 2 PID: 326 Comm: perf Not tainted 5.4.0-rc8-00291-gceb9e773 #904
      > RIP: 0010:bts_buffer_setup_aux+0x117/0x3d0
      > Call Trace:
      >  rb_alloc_aux+0x339/0x550
      >  perf_mmap+0x607/0xc70
      >  mmap_region+0x76b/0xbd0
      ...
      
      It appears to assume (for lost raisins) that PagePrivate() is set,
      while later it actually tests for PagePrivate() before using
      page_private().
      
      Make it consistent and always check PagePrivate() before using
      page_private().
      
      Fixes: 8062382c ("perf/x86/intel/bts: Add BTS PMU driver")
      Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Vince Weaver <vincent.weaver@maine.edu>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
      Link: https://lkml.kernel.org/r/20191205142853.28894-2-alexander.shishkin@linux.intel.comSigned-off-by: default avatarSasha Levin <sashal@kernel.org>
      78880475
    • SeongJae Park's avatar
      xen/blkback: Avoid unmapping unmapped grant pages · 87d43527
      SeongJae Park authored
      [ Upstream commit f9bd84a8 ]
      
      For each I/O request, blkback first maps the foreign pages for the
      request to its local pages.  If an allocation of a local page for the
      mapping fails, it should unmap every mapping already made for the
      request.
      
      However, blkback's handling mechanism for the allocation failure does
      not mark the remaining foreign pages as unmapped.  Therefore, the unmap
      function merely tries to unmap every valid grant page for the request,
      including the pages not mapped due to the allocation failure.  On a
      system that fails the allocation frequently, this problem leads to
      following kernel crash.
      
        [  372.012538] BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
        [  372.012546] IP: [<ffffffff814071ac>] gnttab_unmap_refs.part.7+0x1c/0x40
        [  372.012557] PGD 16f3e9067 PUD 16426e067 PMD 0
        [  372.012562] Oops: 0002 [#1] SMP
        [  372.012566] Modules linked in: act_police sch_ingress cls_u32
        ...
        [  372.012746] Call Trace:
        [  372.012752]  [<ffffffff81407204>] gnttab_unmap_refs+0x34/0x40
        [  372.012759]  [<ffffffffa0335ae3>] xen_blkbk_unmap+0x83/0x150 [xen_blkback]
        ...
        [  372.012802]  [<ffffffffa0336c50>] dispatch_rw_block_io+0x970/0x980 [xen_blkback]
        ...
        Decompressing Linux... Parsing ELF... done.
        Booting the kernel.
        [    0.000000] Initializing cgroup subsys cpuset
      
      This commit fixes this problem by marking the grant pages of the given
      request that didn't mapped due to the allocation failure as invalid.
      
      Fixes: c6cc142d ("xen-blkback: use balloon pages for all mappings")
      Reviewed-by: default avatarDavid Woodhouse <dwmw@amazon.de>
      Reviewed-by: default avatarMaximilian Heyne <mheyne@amazon.de>
      Reviewed-by: default avatarPaul Durrant <pdurrant@amazon.co.uk>
      Reviewed-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
      Signed-off-by: default avatarSeongJae Park <sjpark@amazon.de>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
      87d43527