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Date:   Thu, 13 Feb 2020 14:38:19 +0800
From:   "zhangyi (F)" <>
To:     <>, <>
CC:     <>, <>,
        <>, <>
Subject: [PATCH v3 0/2] jbd2: fix an oops problem

Changes since v2:
 - Back to use "mapping && !sb_is_blkdev_sb(mapping->host->i_sb)" to
   distinguish metadata buffers, and add more comments.
 - Add 'Reviewed-by' to the first patch.

Changes since v1:
 - Switch to clear b_modified just after set_buffer_freed() instead of
   reuse codes at the end of journal_unmap_buffer().
 - Switch to distinguish metadata buffers through the page mapping dev.


Original description:

We encountered a jbd2 oops problem on an aarch64 machine with 4K block
size and 64K page size when doing stress tests.

 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
 user pgtable: 64k pages, 42-bit VAs, pgdp = (____ptrval____)
 pc : jbd2_journal_put_journal_head+0x7c/0x284
 lr : jbd2_journal_put_journal_head+0x3c/0x284
 Call trace:
 Code: 51000400 b9000ac0 35000760 f9402274 (b9400a80)
 ---[ end trace 8fa99273d06aeb63 ]---

These patch set can fix this issue, the first patch is just a cleanup
patch, and the second one describe the root cause and fix it.

zhangyi (F) (2):
  jbd2: move the clearing of b_modified flag to the
  jbd2: do not clear the BH_Mapped flag when forgetting a metadata

 fs/jbd2/commit.c      | 46 +++++++++++++++++++++++--------------------
 fs/jbd2/transaction.c | 10 ++++++----
 2 files changed, 31 insertions(+), 25 deletions(-)


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