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Mon, 28 Jan 2019 16:57:43 +0000 (UTC) Subject: Re: [PATCH] btrfs: clean up pending block groups when transaction commit aborts To: David Sterba , linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org, Josef Bacik References: <20190128164550.17826-1-dsterba@suse.com> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: Date: Mon, 28 Jan 2019 18:57:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190128164550.17826-1-dsterba@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 28.01.19 г. 18:45 ч., David Sterba wrote: > The fstests generic/475 stresses transaction aborts and can reveal > space accounting or use-after-free bugs regarding block goups. > > In this case the pending block groups that remain linked to the > structures after transaction commit aborts in the middle. > > The corrupted slabs lead to failures in following tests, eg. generic/476 > > [ 8172.752887] BUG: unable to handle kernel NULL pointer dereference at 0000000000000058 > [ 8172.755799] #PF error: [normal kernel read fault] > [ 8172.757571] PGD 661ae067 P4D 661ae067 PUD 3db8e067 PMD 0 > [ 8172.759000] Oops: 0000 [#1] PREEMPT SMP > [ 8172.760209] CPU: 0 PID: 39 Comm: kswapd0 Tainted: G W 5.0.0-rc2-default #408 > [ 8172.762495] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014 > [ 8172.765772] RIP: 0010:shrink_page_list+0x2f9/0xe90 > [ 8172.770453] RSP: 0018:ffff967f00663b18 EFLAGS: 00010287 > [ 8172.771184] RAX: 0000000000000000 RBX: ffff967f00663c20 RCX: 0000000000000000 > [ 8172.772850] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8c0620ab20e0 > [ 8172.774629] RBP: ffff967f00663dd8 R08: 0000000000000000 R09: 0000000000000000 > [ 8172.776094] R10: ffff8c0620ab22f8 R11: ffff8c063f772688 R12: ffff967f00663b78 > [ 8172.777533] R13: ffff8c063f625600 R14: ffff8c063f625608 R15: dead000000000200 > [ 8172.778886] FS: 0000000000000000(0000) GS:ffff8c063d400000(0000) knlGS:0000000000000000 > [ 8172.780545] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 8172.781787] CR2: 0000000000000058 CR3: 000000004e962000 CR4: 00000000000006f0 > [ 8172.783547] Call Trace: > [ 8172.784112] shrink_inactive_list+0x194/0x410 > [ 8172.784747] shrink_node_memcg.constprop.85+0x3a5/0x6a0 > [ 8172.785472] shrink_node+0x62/0x1e0 > [ 8172.786011] balance_pgdat+0x216/0x460 > [ 8172.786577] kswapd+0xe3/0x4a0 > [ 8172.787085] ? finish_wait+0x80/0x80 > [ 8172.787795] ? balance_pgdat+0x460/0x460 > [ 8172.788799] kthread+0x116/0x130 > [ 8172.789640] ? kthread_create_on_node+0x60/0x60 > [ 8172.790323] ret_from_fork+0x24/0x30 > [ 8172.794253] CR2: 0000000000000058 > > or accounting errors at umount time: > > [ 8159.537251] WARNING: CPU: 2 PID: 19031 at fs/btrfs/extent-tree.c:5987 btrfs_free_block_groups+0x3d5/0x410 [btrfs] > [ 8159.543325] CPU: 2 PID: 19031 Comm: umount Tainted: G W 5.0.0-rc2-default #408 > [ 8159.545472] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626cc-prebuilt.qemu-project.org 04/01/2014 > [ 8159.548155] RIP: 0010:btrfs_free_block_groups+0x3d5/0x410 [btrfs] > [ 8159.554030] RSP: 0018:ffff967f079cbde8 EFLAGS: 00010206 > [ 8159.555144] RAX: 0000000001000000 RBX: ffff8c06366cf800 RCX: 0000000000000000 > [ 8159.556730] RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff8c06255ad800 > [ 8159.558279] RBP: ffff8c0637ac0000 R08: 0000000000000001 R09: 0000000000000000 > [ 8159.559797] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8c0637ac0108 > [ 8159.561296] R13: ffff8c0637ac0158 R14: 0000000000000000 R15: dead000000000100 > [ 8159.562852] FS: 00007f7f693b9fc0(0000) GS:ffff8c063d800000(0000) knlGS:0000000000000000 > [ 8159.564839] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 8159.566160] CR2: 00007f7f68fab7b0 CR3: 000000000aec7000 CR4: 00000000000006e0 > [ 8159.567898] Call Trace: > [ 8159.568597] close_ctree+0x17f/0x350 [btrfs] > [ 8159.569628] generic_shutdown_super+0x64/0x100 > [ 8159.570808] kill_anon_super+0x14/0x30 > [ 8159.571857] btrfs_kill_super+0x12/0xa0 [btrfs] > [ 8159.573063] deactivate_locked_super+0x29/0x60 > [ 8159.574234] cleanup_mnt+0x3b/0x70 > [ 8159.575176] task_work_run+0x98/0xc0 > [ 8159.576177] exit_to_usermode_loop+0x83/0x90 > [ 8159.577315] do_syscall_64+0x15b/0x180 > [ 8159.578339] entry_SYSCALL_64_after_hwframe+0x49/0xbe > > This fix is based on 2 Josef's patches that used sideefects of > btrfs_create_pending_block_groups, this fix introduces the helper that > does what we need. > > CC: stable@vger.kernel.org # 4.4+ > CC: Josef Bacik > Signed-off-by: David Sterba > --- > fs/btrfs/transaction.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c > index 127fa1535f58..1c23f227525c 100644 > --- a/fs/btrfs/transaction.c > +++ b/fs/btrfs/transaction.c > @@ -1895,6 +1895,20 @@ static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info) > return 0; > } > > +static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans) > +{ > + struct btrfs_fs_info *fs_info = trans->fs_info; > + struct btrfs_block_group_cache *block_group; > + > + while (!list_empty(&trans->new_bgs)) { > + block_group = list_first_entry(&trans->new_bgs, > + struct btrfs_block_group_cache, > + bg_list); > + btrfs_delayed_refs_rsv_release(fs_info, 1); > + list_del_init(&block_group->bg_list); > + } > +} This is much cleaner and understandable, thanks. nit:Can't we use list_for_each_entry_safe though and save the explicit list_first_entry. IMO this is fine here since the transaction is aborted hence no new pending bgs can be added to the ->new_bgs list. In any case: Reviewed-by: Nikolay Borisov > + > static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info) > { > if (btrfs_test_opt(fs_info, FLUSHONCOMMIT)) > @@ -2270,6 +2284,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) > btrfs_scrub_continue(fs_info); > cleanup_transaction: > btrfs_trans_release_metadata(trans); > + btrfs_cleanup_pending_block_groups(trans); > btrfs_trans_release_chunk_metadata(trans); > trans->block_rsv = NULL; > btrfs_warn(fs_info, "Skipping commit of aborted transaction."); >