Re: [PATCH v3 5/6] maple_tree: add sufficient height
From: Sidhartha Kumar
Date: Mon Mar 10 2025 - 17:02:23 EST
On 3/10/25 2:13 PM, Vasily Gorbik wrote:
On Thu, Feb 27, 2025 at 08:48:22PM +0000, Sidhartha Kumar wrote:
In order to support rebalancing and spanning stores using less than the
worst case number of nodes, we need to track more than just the vacant
height. Using only vacant height to reduce the worst case maple node
allocation count can lead to a shortcoming of nodes in the following
scenarios.
...
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
---
include/linux/maple_tree.h | 4 +++-
lib/maple_tree.c | 17 +++++++++++++++--
tools/testing/radix-tree/maple.c | 28 ++++++++++++++++++++++++++++
3 files changed, 46 insertions(+), 3 deletions(-)
Hi Sidhartha,
Starting from this commit, the LTP test "linkat02" consistently triggers
a kernel WARNING followed by a crash, at least on s390 (and probably on
other big-endian architectures as well). The maple tree selftest passes
successfully.
Hi,
Thanks for reporting this, it looks like it doesn't reproduce on x86 so
I'll try to virtualize s390 to reproduce. Andrew, could you revert this
series from mm-unstable as I work on fixing this?
Thanks,
Sid
[ 233.489583] LTP: starting linkat02
linkat02 0 TINFO : Using /tmp/ltp-8P2ZJL0mgN/LTP_lin3flG7N as tmpdir (tmpfs filesystem)
linkat02 0 TINFO : Found free device 0 '/dev/loop0'
[ 234.187957] loop0: detected capacity change from 0 to 614400
linkat02 0 TINFO : Formatting /dev/loop0 with ext2 opts='' extra opts=''
mke2fs 1.47.1 (20-May-2024)
[ 234.571157] operation not supported error, dev loop0, sector 614272 op 0x9:(WRITE_ZEROES) flags 0x10000800 phys_seg 0 prio class 0
linkat02 0 TINFO : Mounting /dev/loop0 to /tmp/ltp-8P2ZJL0mgN/LTP_lin3flG7N/mntpoint fstyp=ext2 flags=0
[ 234.690816] EXT4-fs (loop0): mounting ext2 file system using the ext4 subsystem
[ 234.696090] EXT4-fs (loop0): mounted filesystem 29120d07-e10b-43b8-bfb0-6156683a2769 r/w without journal. Quota mode: none.
linkat02 0 TINFO : Failed reach the hardlinks limit
[ 239.616047] ------------[ cut here ]------------
[ 239.616231] WARNING: CPU: 0 PID: 669 at lib/maple_tree.c:1156 mas_pop_node+0x220/0x290
[ 239.616252] Modules linked in:
[ 239.616292] CPU: 0 UID: 0 PID: 669 Comm: linkat02 Not tainted 6.14.0-rc5-next-20250307 #29
[ 239.616305] Hardware name: IBM 3931 A01 704 (KVM/Linux)
[ 239.616315] Krnl PSW : 0704c00180000000 00007fffe2b6c314 (mas_pop_node+0x224/0x290)
[ 239.616334] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
[ 239.616349] Krnl GPRS: 0000000000000005 001c0feffc355f67 00007f7fe1aafb38 001c000000000000
[ 239.616360] 001c000000000000 001c0fef00007f05 0000000000000000 ffffffffffffffff
[ 239.616371] 00007f7fe1aaf3e0 00007f7fe1aafb08 001c000000000000 0000000000000000
[ 239.616381] 0000000001026838 0000000000000005 00007f7fe1aaf020 00007f7fe1aaefc8
[ 239.616399] Krnl Code: 00007fffe2b6c306: e370a0000024 stg %r7,0(%r10)
[ 239.616399] 00007fffe2b6c30c: a7f4ff83 brc 15,00007fffe2b6c212
[ 239.616399] #00007fffe2b6c310: af000000 mc 0,0
[ 239.616399] >00007fffe2b6c314: a7b90000 lghi %r11,0
[ 239.616399] 00007fffe2b6c318: a7f4ff89 brc 15,00007fffe2b6c22a
[ 239.616399] 00007fffe2b6c31c: c0e5fefc1f8a brasl %r14,00007fffe0af0230
[ 239.616399] 00007fffe2b6c322: a7f4ff4b brc 15,00007fffe2b6c1b8
[ 239.616399] 00007fffe2b6c326: c0e5fefc1fa5 brasl %r14,00007fffe0af0270
[ 239.616454] Call Trace:
[ 239.616463] [<00007fffe2b6c314>] mas_pop_node+0x224/0x290
[ 239.616475] [<00007fffe2b85ab6>] mas_spanning_rebalance+0x3006/0x4e90
[ 239.616487] [<00007fffe2b87e7a>] mas_rebalance+0x53a/0x9c0
[ 239.616627] [<00007fffe2b8c10a>] mas_wr_bnode+0x14a/0x1a0
[ 239.616639] [<00007fffe2b9a87c>] mas_erase+0xd9c/0x1120
[ 239.616650] [<00007fffe2b9acbe>] mtree_erase+0xbe/0xf0
[ 239.616661] [<00007fffe0c3b4d2>] simple_offset_remove+0x52/0x90
[ 239.616674] [<00007fffe093dc16>] shmem_unlink+0xb6/0x320
[ 239.616686] [<00007fffe0bc0830>] vfs_unlink+0x270/0x760
[ 239.616698] [<00007fffe0bd473a>] do_unlinkat+0x40a/0x5c0
[ 239.616709] [<00007fffe0bd4a48>] __s390x_sys_unlink+0x58/0x70
[ 239.616720] [<00007fffe0155356>] do_syscall+0x2f6/0x430
[ 239.616733] [<00007fffe2bd3668>] __do_syscall+0xc8/0x1c0
[ 239.616746] [<00007fffe2bf70d4>] system_call+0x74/0x98
[ 239.616758] 4 locks held by linkat02/669:
[ 239.616769] #0: 0000780097e89450 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x4c/0xc0
[ 239.616799] #1: 00007800a7de6cd0 (&type->i_mutex_dir_key#5/1){+.+.}-{3:3}, at: do_unlinkat+0x1f8/0x5c0
[ 239.616831] #2: 00007800a7de7ac0 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: vfs_unlink+0xc6/0x760
[ 239.616860] #3: 00007800a7de6a58 (&simple_offset_lock_class){+.+.}-{2:2}, at: mtree_erase+0xb4/0xf0
[ 239.616886] Last Breaking-Event-Address:
[ 239.616895] [<00007fffe2b6c12a>] mas_pop_node+0x3a/0x290
[ 239.616909] irq event stamp: 5205821
[ 239.616918] hardirqs last enabled at (5205831): [<00007fffe03d2be8>] __up_console_sem+0xe8/0x130
[ 239.616931] hardirqs last disabled at (5205840): [<00007fffe03d2bc6>] __up_console_sem+0xc6/0x130
[ 239.616943] softirqs last enabled at (5200824): [<00007fffe0246b6c>] handle_softirqs+0x6dc/0xe30
[ 239.616955] softirqs last disabled at (5200687): [<00007fffe024508a>] __irq_exit_rcu+0x34a/0x3f0
[ 239.616994] ---[ end trace 0000000000000000 ]---
[ 239.617009] Unable to handle kernel pointer dereference in virtual kernel address space
[ 239.617019] Failing address: 0000000000000000 TEID: 0000000000000483
[ 239.617029] Fault in home space mode while using kernel ASCE.
[ 239.617049] AS:0000000005dac00b R2:00000001ffffc00b R3:00000001ffff8007 S:00000001ffff7801 P:000000000000013d
[ 239.617150] Oops: 0004 ilc:3 [#1] PREEMPT SMP
[ 239.617162] Modules linked in:
[ 239.617170] CPU: 0 UID: 0 PID: 669 Comm: linkat02 Tainted: G W 6.14.0-rc5-next-20250307 #29
[ 239.617243] Tainted: [W]=WARN
[ 239.617248] Hardware name: IBM 3931 A01 704 (KVM/Linux)
[ 239.617253] Krnl PSW : 0704c00180000000 00007fffe2b6a988 (mab_mas_cp+0x168/0x640)
[ 239.617264] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
[ 239.617272] Krnl GPRS: 0000000000000008 0000000000000000 00007fff00000008 00007f7f00000009
[ 239.617279] 0000000000000008 001c000000000000 0000000000000008 0000000000000048
[ 239.617285] 001c0ffffc638e09 001c000000000009 0000000000000098 001c000000000000
[ 239.617292] 0000000001026838 00007f7fe1aaf608 001c000000000013 00007f7fe1aaef68
[ 239.617302] Krnl Code: 00007fffe2b6a97c: b90800e5 agr %r14,%r5
[ 239.617302] 00007fffe2b6a980: 9500e000 cli 0(%r14),0
[ 239.617302] #00007fffe2b6a984: a7740262 brc 7,00007fffe2b6ae48
[ 239.617302] >00007fffe2b6a988: e548a0000000 mvghi 0(%r10),0
[ 239.617302] 00007fffe2b6a98e: e3a0f0c00004 lg %r10,192(%r15)
[ 239.617302] 00007fffe2b6a994: a7b80000 lhi %r11,0
[ 239.617302] 00007fffe2b6a998: eb2a0003000d sllg %r2,%r10,3
[ 239.617302] 00007fffe2b6a99e: e320f0f00024 stg %r2,240(%r15)
[ 239.617350] Call Trace:
[ 239.617354] [<00007fffe2b6a988>] mab_mas_cp+0x168/0x640
[ 239.617362] [<00007fffe2b85bcc>] mas_spanning_rebalance+0x311c/0x4e90
[ 239.617369] [<00007fffe2b87e7a>] mas_rebalance+0x53a/0x9c0
[ 239.617376] [<00007fffe2b8c10a>] mas_wr_bnode+0x14a/0x1a0
[ 239.617383] [<00007fffe2b9a87c>] mas_erase+0xd9c/0x1120
[ 239.617389] [<00007fffe2b9acbe>] mtree_erase+0xbe/0xf0
[ 239.617396] [<00007fffe0c3b4d2>] simple_offset_remove+0x52/0x90
[ 239.617403] [<00007fffe093dc16>] shmem_unlink+0xb6/0x320
[ 239.617410] [<00007fffe0bc0830>] vfs_unlink+0x270/0x760
[ 239.617416] [<00007fffe0bd473a>] do_unlinkat+0x40a/0x5c0
[ 239.617422] [<00007fffe0bd4a48>] __s390x_sys_unlink+0x58/0x70
[ 239.617429] [<00007fffe0155356>] do_syscall+0x2f6/0x430
[ 239.617436] [<00007fffe2bd3668>] __do_syscall+0xc8/0x1c0
[ 239.617443] [<00007fffe2bf70d4>] system_call+0x74/0x98
[ 239.617450] INFO: lockdep is turned off.
[ 239.617454] Last Breaking-Event-Address:
[ 239.617458] [<00007fffe2b6a8f4>] mab_mas_cp+0xd4/0x640
[ 239.617468] Kernel panic - not syncing: Fatal exception: panic_on_oops