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zhangyi (F) c96dceeabf jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer 
Commit 904cdbd41d ("jbd2: clear dirty flag when revoking a buffer from
an older transaction") set the BH_Freed flag when forgetting a metadata
buffer which belongs to the committing transaction, it indicate the
committing process clear dirty bits when it is done with the buffer. But
it also clear the BH_Mapped flag at the same time, which may trigger
below NULL pointer oops when block_size < PAGE_SIZE.

rmdir 1             kjournald2                 mkdir 2
                    jbd2_journal_commit_transaction
		    commit transaction N
jbd2_journal_forget
set_buffer_freed(bh1)
                    jbd2_journal_commit_transaction
                     commit transaction N+1
                     ...
                     clear_buffer_mapped(bh1)
                                               ext4_getblk(bh2 ummapped)
                                               ...
                                               grow_dev_page
                                                init_page_buffers
                                                 bh1->b_private=NULL
                                                 bh2->b_private=NULL
                     jbd2_journal_put_journal_head(jh1)
                      __journal_remove_journal_head(hb1)
		       jh1 is NULL and trigger oops

*) Dir entry block bh1 and bh2 belongs to one page, and the bh2 has
   already been unmapped.

For the metadata buffer we forgetting, we should always keep the mapped
flag and clear the dirty flags is enough, so this patch pick out the
these buffers and keep their BH_Mapped flag.

Link: https://lore.kernel.org/r/20200213063821.30455-3-yi.zhang@huawei.com
Fixes: 904cdbd41d ("jbd2: clear dirty flag when revoking a buffer from an older transaction")
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
2020-02-13 12:06:28 -05:00
arch drm pull for 5.6-rc1 2020-01-30 08:04:01 -08:00
block SCSI misc on 20200129 2020-01-29 18:16:16 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-01-28 15:38:56 -08:00
Documentation This merge window, we've added some performance improvements in how we 2020-01-30 15:17:05 -08:00
drivers drm pull for 5.6-rc1 2020-01-30 08:04:01 -08:00
fs jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer 2020-02-13 12:06:28 -05:00
include This merge window, we've added some performance improvements in how we 2020-01-30 15:17:05 -08:00
init Driver core changes for 5.6-rc1 2020-01-29 10:18:20 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel hmm related patches for 5.6 2020-01-29 19:56:50 -08:00
lib linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm hmm related patches for 5.6 2020-01-29 19:56:50 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-30 07:42:00 -08:00
samples drm pull for 5.6-rc1 2020-01-30 08:04:01 -08:00
scripts Devicetree updates for v5.6: 2020-01-30 07:47:58 -08:00
security linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
sound sound updates for 5.6-rc1 2020-01-28 16:26:57 -08:00
tools drm pull for 5.6-rc1 2020-01-30 08:04:01 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-01-28 15:38:56 -08:00
COPYING
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS drm pull for 5.6-rc1 2020-01-30 08:04:01 -08:00
Makefile Linux 5.5 2020-01-26 16:23:03 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.