summaryrefslogtreecommitdiffstats
path: root/mm/internal.h
diff options
context:
space:
mode:
authorRoss Zwisler <ross.zwisler@linux.intel.com>2017-01-10 16:57:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-10 18:31:54 -0800
commitf729c8c9b24f0540a6e6b86e68f3888ba90ef7e7 (patch)
tree8dd956224ce2b958954c5bfe0b7cf1809299dce6 /mm/internal.h
parent097963959594c5eccaba42510f7033f703211bda (diff)
downloadop-kernel-dev-f729c8c9b24f0540a6e6b86e68f3888ba90ef7e7.zip
op-kernel-dev-f729c8c9b24f0540a6e6b86e68f3888ba90ef7e7.tar.gz
dax: wrprotect pmd_t in dax_mapping_entry_mkclean
Currently dax_mapping_entry_mkclean() fails to clean and write protect the pmd_t of a DAX PMD entry during an *sync operation. This can result in data loss in the following sequence: 1) mmap write to DAX PMD, dirtying PMD radix tree entry and making the pmd_t dirty and writeable 2) fsync, flushing out PMD data and cleaning the radix tree entry. We currently fail to mark the pmd_t as clean and write protected. 3) more mmap writes to the PMD. These don't cause any page faults since the pmd_t is dirty and writeable. The radix tree entry remains clean. 4) fsync, which fails to flush the dirty PMD data because the radix tree entry was clean. 5) crash - dirty data that should have been fsync'd as part of 4) could still have been in the processor cache, and is lost. Fix this by marking the pmd_t clean and write protected in dax_mapping_entry_mkclean(), which is called as part of the fsync operation 2). This will cause the writes in step 3) above to generate page faults where we'll re-dirty the PMD radix tree entry, resulting in flushes in the fsync that happens in step 4). Fixes: 4b4bb46d00b3 ("dax: clear dirty entry tags on cache flush") Link: http://lkml.kernel.org/r/1482272586-21177-3-git-send-email-ross.zwisler@linux.intel.com Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/internal.h')
0 files changed, 0 insertions, 0 deletions
OpenPOWER on IntegriCloud