Kernel panic in page_buffers function during writeback due to an application pinning pages via RDMA or mmap and writing to them outside normal Linux kernel filesystem interfaces

Solution In Progress - Updated -

Issue

  • Kernel BUG during writeback due to BUG_ON(!PagePrivate(page))
  • Kernel crashes with kernel BUG at fs/ext4/inode.c:2244! crashing in mpage_prepare_extent_to_map+0x2d5/0x2e0 [ext4] called from ext4_writepages

Environment

  • Red Hat Enterprise Linux 8
    • all kernels believed to be affected
  • Red Hat Enterprise Linux 7
    • all kernels believed to be affected
    • seen on at least 3.10.0-693.17.1.el7.x86_64, 3.10.0-514.2.2.el7.x86_64 and 3.10.0-327.28.2.el7.x86_64
  • seen often with ext4, but not specific to ext4
  • applications writing directly (RDMA or mmap) to pages that are part of a filesystem

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