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Date:   Tue, 7 Jan 2020 04:47:08 -0800
From:   Guenter Roeck <linux@roeck-us.net>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, Chris Mason <clm@fb.com>
Subject: Re: [PATCH] block: fix splitting segments
Message-ID: <20200107124708.GA20285@roeck-us.net>
References: <20191229023230.28940-1-ming.lei@redhat.com>
MIME-Version: 1.0
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In-Reply-To: <20191229023230.28940-1-ming.lei@redhat.com>
User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi,

On Sun, Dec 29, 2019 at 10:32:30AM +0800, Ming Lei wrote:
> There are two issues in get_max_segment_size():
> 
> 1) the default segment boudary mask is bypassed, and some devices still
> require segment to not cross the default 4G boundary
> 
> 2) the segment start address isn't taken into account when checking
> segment boundary limit
> 
> Fixes the two issues.
> 
> Fixes: dcebd755926b ("block: use bio_for_each_bvec() to compute multi-page bvec count")
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

This patch, pushed into mainline as "block: fix splitting segments on
boundary masks", results in the following crash when booting 'versatilepb'
in qemu from disk. Bisect log is attached. Detailed log is at
https://kerneltests.org/builders/qemu-arm-master/builds/1410/steps/qemubuildcommand/logs/stdio

Guenter

---
Crash:

kernel BUG at block/bio.c:1885!
Internal error: Oops - BUG: 0 [#1] ARM
Modules linked in:
CPU: 0 PID: 1 Comm: init Not tainted 5.5.0-rc5 #1
Hardware name: ARM-Versatile (Device Tree Support)
PC is at bio_split+0x10c/0x15c
LR is at __blk_queue_split+0x378/0x628
...
[<c03b716c>] (bio_split) from [<c03c24c8>] (__blk_queue_split+0x378/0x628)
[<c03c24c8>] (__blk_queue_split) from [<c03c82cc>] (blk_mq_make_request+0x6c/0x7e4)
[<c03c82cc>] (blk_mq_make_request) from [<c03bc7d0>] (generic_make_request+0xec/0x340)
[<c03bc7d0>] (generic_make_request) from [<c03bca70>] (submit_bio+0x4c/0x170)
[<c03bca70>] (submit_bio) from [<c020666c>] (ext4_mpage_readpages+0x54c/0x8e0)
[<c020666c>] (ext4_mpage_readpages) from [<c01e1ec8>] (ext4_readpages+0x40/0x50)
[<c01e1ec8>] (ext4_readpages) from [<c00df808>] (read_pages+0x50/0x13c)
[<c00df808>] (read_pages) from [<c00dfd2c>] (__do_page_cache_readahead+0x1a8/0x1f0)
[<c00dfd2c>] (__do_page_cache_readahead) from [<c00d500c>] (filemap_fault+0x440/0x8f4)
[<c00d500c>] (filemap_fault) from [<c01ed494>] (ext4_filemap_fault+0x28/0x3c)
[<c01ed494>] (ext4_filemap_fault) from [<c0100b88>] (__do_fault+0x3c/0x1c0)
[<c0100b88>] (__do_fault) from [<c0105360>] (handle_mm_fault+0x284/0xaf4)
[<c0105360>] (handle_mm_fault) from [<c001f01c>] (do_page_fault+0x114/0x2e0)
[<c001f01c>] (do_page_fault) from [<c001f34c>] (do_DataAbort+0x38/0xbc)
[<c001f34c>] (do_DataAbort) from [<c000a0dc>] (__dabt_svc+0x5c/0xa0)
Exception stack(0xc783be28 to 0xc783be70)
be20:                   b6f81898 00000760 00000000 00000055 00000051 c0af3068
be40: c71f7a00 c71f7800 b6f51000 c71df320 c7954c80 00000006 00000000 c783be78
be60: c01a099c c07a4bb4 20000153 ffffffff
[<c000a0dc>] (__dabt_svc) from [<c07a4bb4>] (__clear_user_std+0x34/0x68)
[<c07a4bb4>] (__clear_user_std) from [<c01a099c>] (clear_user+0x40/0x50)
[<c01a099c>] (clear_user) from [<c019f204>] (load_elf_binary+0x1354/0x13c4)
[<c019f204>] (load_elf_binary) from [<c013996c>] (search_binary_handler.part.4+0x58/0x1fc)
[<c013996c>] (search_binary_handler.part.4) from [<c013b18c>] (__do_execve_file+0x780/0x9a4)
[<c013b18c>] (__do_execve_file) from [<c013b54c>] (do_execve+0x28/0x30)
[<c013b54c>] (do_execve) from [<c000af1c>] (try_to_run_init_process+0xc/0x3c)
[<c000af1c>] (try_to_run_init_process) from [<c07c42fc>] (kernel_init+0x88/0xf0)
[<c07c42fc>] (kernel_init) from [<c00090b0>] (ret_from_fork+0x14/0x24)
...
WARNING: CPU: 0 PID: 1 at kernel/exit.c:719 do_exit+0x54/0xb5c
Modules linked in:
CPU: 0 PID: 1 Comm: init Tainted: G      D           5.5.0-rc5 #1
Hardware name: ARM-Versatile (Device Tree Support)
[<c001e8b0>] (unwind_backtrace) from [<c001a774>] (show_stack+0x10/0x14)
[<c001a774>] (show_stack) from [<c0027dc4>] (__warn+0xe4/0x108)
[<c0027dc4>] (__warn) from [<c0027e90>] (warn_slowpath_fmt+0xa8/0xb8)
[<c0027e90>] (warn_slowpath_fmt) from [<c0029dfc>] (do_exit+0x54/0xb5c)
[<c0029dfc>] (do_exit) from [<c001a918>] (die+0x1a0/0x274)
[<c001a918>] (die) from [<c001abfc>] (do_undefinstr+0xac/0x258)
[<c001abfc>] (do_undefinstr) from [<c000a238>] (__und_svc_finish+0x0/0x48)
Exception stack(0xc783b950 to 0xc783b998)
b940:                                     c7226a80 00000000 00000c00 c7bebe00
b960: 00000000 c783b9e4 00000000 c7226a80 00007000 00000060 c7beb848 c783b9f0
b980: 00000060 c783b9a0 c03c24c8 c03b716c 60000153 ffffffff
[<c000a238>] (__und_svc_finish) from [<c03b716c>] (bio_split+0x10c/0x15c)
[<c03b716c>] (bio_split) from [<c03c24c8>] (__blk_queue_split+0x378/0x628)
[<c03c24c8>] (__blk_queue_split) from [<c03c82cc>] (blk_mq_make_request+0x6c/0x7e4)
[<c03c82cc>] (blk_mq_make_request) from [<c03bc7d0>] (generic_make_request+0xec/0x340)
[<c03bc7d0>] (generic_make_request) from [<c03bca70>] (submit_bio+0x4c/0x170)
[<c03bca70>] (submit_bio) from [<c020666c>] (ext4_mpage_readpages+0x54c/0x8e0)
[<c020666c>] (ext4_mpage_readpages) from [<c01e1ec8>] (ext4_readpages+0x40/0x50)
[<c01e1ec8>] (ext4_readpages) from [<c00df808>] (read_pages+0x50/0x13c)
[<c00df808>] (read_pages) from [<c00dfd2c>] (__do_page_cache_readahead+0x1a8/0x1f0)
[<c00dfd2c>] (__do_page_cache_readahead) from [<c00d500c>] (filemap_fault+0x440/0x8f4)
[<c00d500c>] (filemap_fault) from [<c01ed494>] (ext4_filemap_fault+0x28/0x3c)
[<c01ed494>] (ext4_filemap_fault) from [<c0100b88>] (__do_fault+0x3c/0x1c0)
[<c0100b88>] (__do_fault) from [<c0105360>] (handle_mm_fault+0x284/0xaf4)
[<c0105360>] (handle_mm_fault) from [<c001f01c>] (do_page_fault+0x114/0x2e0)
[<c001f01c>] (do_page_fault) from [<c001f34c>] (do_DataAbort+0x38/0xbc)
[<c001f34c>] (do_DataAbort) from [<c000a0dc>] (__dabt_svc+0x5c/0xa0)
Exception stack(0xc783be28 to 0xc783be70)
be20:                   b6f81898 00000760 00000000 00000055 00000051 c0af3068
be40: c71f7a00 c71f7800 b6f51000 c71df320 c7954c80 00000006 00000000 c783be78
be60: c01a099c c07a4bb4 20000153 ffffffff
[<c000a0dc>] (__dabt_svc) from [<c07a4bb4>] (__clear_user_std+0x34/0x68)
[<c07a4bb4>] (__clear_user_std) from [<c01a099c>] (clear_user+0x40/0x50)
[<c01a099c>] (clear_user) from [<c019f204>] (load_elf_binary+0x1354/0x13c4)
[<c019f204>] (load_elf_binary) from [<c013996c>] (search_binary_handler.part.4+0x58/0x1fc)
[<c013996c>] (search_binary_handler.part.4) from [<c013b18c>] (__do_execve_file+0x780/0x9a4)
[<c013b18c>] (__do_execve_file) from [<c013b54c>] (do_execve+0x28/0x30)
[<c013b54c>] (do_execve) from [<c000af1c>] (try_to_run_init_process+0xc/0x3c)
[<c000af1c>] (try_to_run_init_process) from [<c07c42fc>] (kernel_init+0x88/0xf0)
[<c07c42fc>] (kernel_init) from [<c00090b0>] (ret_from_fork+0x14/0x24)
Exception stack(0xc783bfb0 to 0xc783bff8)
bfa0:                                     00000000 00000000 00000000 00000000
bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
irq event stamp: 159876
hardirqs last  enabled at (159875): [<c009123c>] ktime_get+0x74/0x16c
hardirqs last disabled at (159876): [<c000a21c>] __und_svc+0x5c/0x70
softirqs last  enabled at (159728): [<c000aaf0>] __do_softirq+0x308/0x4bc
softirqs last disabled at (159697): [<c002cf94>] irq_exit+0x150/0x178
---[ end trace 42dd349d5c0726c1 ]---
BUG: sleeping function called from invalid context at ./include/linux/cgroup-defs.h:747
in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 1, name: init
INFO: lockdep is turned off.
irq event stamp: 159876
hardirqs last  enabled at (159875): [<c009123c>] ktime_get+0x74/0x16c
hardirqs last disabled at (159876): [<c000a21c>] __und_svc+0x5c/0x70
softirqs last  enabled at (159728): [<c000aaf0>] __do_softirq+0x308/0x4bc
softirqs last disabled at (159697): [<c002cf94>] irq_exit+0x150/0x178
CPU: 0 PID: 1 Comm: init Tainted: G      D W         5.5.0-rc5 #1
Hardware name: ARM-Versatile (Device Tree Support)
[<c001e8b0>] (unwind_backtrace) from [<c001a774>] (show_stack+0x10/0x14)
[<c001a774>] (show_stack) from [<c004fc4c>] (___might_sleep+0x1a8/0x2bc)
[<c004fc4c>] (___might_sleep) from [<c00380d0>] (exit_signals+0x28/0x134)
[<c00380d0>] (exit_signals) from [<c0029e70>] (do_exit+0xc8/0xb5c)
[<c0029e70>] (do_exit) from [<c001a918>] (die+0x1a0/0x274)
[<c001a918>] (die) from [<c001abfc>] (do_undefinstr+0xac/0x258)
[<c001abfc>] (do_undefinstr) from [<c000a238>] (__und_svc_finish+0x0/0x48)
Exception stack(0xc783b950 to 0xc783b998)
b940:                                     c7226a80 00000000 00000c00 c7bebe00
b960: 00000000 c783b9e4 00000000 c7226a80 00007000 00000060 c7beb848 c783b9f0
b980: 00000060 c783b9a0 c03c24c8 c03b716c 60000153 ffffffff
[<c000a238>] (__und_svc_finish) from [<c03b716c>] (bio_split+0x10c/0x15c)
[<c03b716c>] (bio_split) from [<c03c24c8>] (__blk_queue_split+0x378/0x628)
[<c03c24c8>] (__blk_queue_split) from [<c03c82cc>] (blk_mq_make_request+0x6c/0x7e4)
[<c03c82cc>] (blk_mq_make_request) from [<c03bc7d0>] (generic_make_request+0xec/0x340)
[<c03bc7d0>] (generic_make_request) from [<c03bca70>] (submit_bio+0x4c/0x170)
[<c03bca70>] (submit_bio) from [<c020666c>] (ext4_mpage_readpages+0x54c/0x8e0)
[<c020666c>] (ext4_mpage_readpages) from [<c01e1ec8>] (ext4_readpages+0x40/0x50)
[<c01e1ec8>] (ext4_readpages) from [<c00df808>] (read_pages+0x50/0x13c)
[<c00df808>] (read_pages) from [<c00dfd2c>] (__do_page_cache_readahead+0x1a8/0x1f0)
[<c00dfd2c>] (__do_page_cache_readahead) from [<c00d500c>] (filemap_fault+0x440/0x8f4)
[<c00d500c>] (filemap_fault) from [<c01ed494>] (ext4_filemap_fault+0x28/0x3c)
[<c01ed494>] (ext4_filemap_fault) from [<c0100b88>] (__do_fault+0x3c/0x1c0)
[<c0100b88>] (__do_fault) from [<c0105360>] (handle_mm_fault+0x284/0xaf4)
[<c0105360>] (handle_mm_fault) from [<c001f01c>] (do_page_fault+0x114/0x2e0)
[<c001f01c>] (do_page_fault) from [<c001f34c>] (do_DataAbort+0x38/0xbc)
[<c001f34c>] (do_DataAbort) from [<c000a0dc>] (__dabt_svc+0x5c/0xa0)
Exception stack(0xc783be28 to 0xc783be70)
be20:                   b6f81898 00000760 00000000 00000055 00000051 c0af3068
be40: c71f7a00 c71f7800 b6f51000 c71df320 c7954c80 00000006 00000000 c783be78
be60: c01a099c c07a4bb4 20000153 ffffffff
[<c000a0dc>] (__dabt_svc) from [<c07a4bb4>] (__clear_user_std+0x34/0x68)
[<c07a4bb4>] (__clear_user_std) from [<c01a099c>] (clear_user+0x40/0x50)
[<c01a099c>] (clear_user) from [<c019f204>] (load_elf_binary+0x1354/0x13c4)
[<c019f204>] (load_elf_binary) from [<c013996c>] (search_binary_handler.part.4+0x58/0x1fc)
[<c013996c>] (search_binary_handler.part.4) from [<c013b18c>] (__do_execve_file+0x780/0x9a4)
[<c013b18c>] (__do_execve_file) from [<c013b54c>] (do_execve+0x28/0x30)
[<c013b54c>] (do_execve) from [<c000af1c>] (try_to_run_init_process+0xc/0x3c)
[<c000af1c>] (try_to_run_init_process) from [<c07c42fc>] (kernel_init+0x88/0xf0)
[<c07c42fc>] (kernel_init) from [<c00090b0>] (ret_from_fork+0x14/0x24)
Exception stack(0xc783bfb0 to 0xc783bff8)
bfa0:                                     00000000 00000000 00000000 00000000
bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

---
bisect log:

# bad: [ae6088216ce4b99b3a4aaaccd2eb2dd40d473d42] Merge tag 'trace-v5.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
# good: [738d2902773e30939a982c8df7a7f94293659810] Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
git bisect start 'HEAD' '738d2902773e'
# bad: [84029fd04c201a4c7e0b07ba262664900f47c6f5] memcg: account security cred as well to kmemcg
git bisect bad 84029fd04c201a4c7e0b07ba262664900f47c6f5
# good: [e35d0165908ad2d2bdb76773ef77b551763eedbd] Merge tag 'sound-5.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
git bisect good e35d0165908ad2d2bdb76773ef77b551763eedbd
# bad: [3a562aee727a7bfbb3a37b1aa934118397dad701] Merge tag 'for-5.5-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
git bisect bad 3a562aee727a7bfbb3a37b1aa934118397dad701
# good: [bed723519a72c0f68fbfaf68ed5bf55d04e46566] Merge tag 'kbuild-fixes-v5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
git bisect good bed723519a72c0f68fbfaf68ed5bf55d04e46566
# bad: [b6b4aafc99d7c8dbf7d9429bf054b591daab1ad0] Merge tag 'block-5.5-20200103' of git://git.kernel.dk/linux-block
git bisect bad b6b4aafc99d7c8dbf7d9429bf054b591daab1ad0
# bad: [429120f3df2dba2bf3a4a19f4212a53ecefc7102] block: fix splitting segments on boundary masks
git bisect bad 429120f3df2dba2bf3a4a19f4212a53ecefc7102
# good: [85a8ce62c2eabe28b9d76ca4eecf37922402df93] block: add bio_truncate to fix guard_bio_eod
git bisect good 85a8ce62c2eabe28b9d76ca4eecf37922402df93
# first bad commit: [429120f3df2dba2bf3a4a19f4212a53ecefc7102] block: fix splitting segments on boundary masks