Re: [PATCH v13 2/9] f2fs: Simplify the handling of cached insensitive names

[Eugen Hristev]

On 3/14/24 01:36, Gabriel Krisman Bertazi wrote:
> Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> writes:
> 
>> +void f2fs_free_casefolded_name(struct f2fs_filename *fname)
>> +{
>> +	unsigned char *buf = (unsigned char *)fname->cf_name.name;
>> +
>> +	kmem_cache_free(f2fs_cf_name_slab, buf);
>> +	fname->cf_name.name = NULL;
> 
> In my previous review, I mentioned you could drop the "if (buf)" check
> here *if and only if* you used kfree. By doing an unchecked kmem_cache_free
> like this, you will immediately hit an Oops in the first lookup (see below).
> 
> Please, make sure you actually stress test this patchset with fstests
> against both f2fs and ext4 before sending each new version.

I did run the xfstests, however, maybe I did not run the full suite, or maybe I am
running it in a wrong way ?
How are you running the kvm-xfstests with qemu ? Can you share your command
arguments please ?

Thanks

> 
> Thanks,
> 
> 
> [   74.202044] F2FS-fs (loop0): Using encoding defined by superblock: utf8-12.1.0 with flags 0x0
> [   74.206592] F2FS-fs (loop0): Found nat_bits in checkpoint
> [   74.221467] F2FS-fs (loop0): Mounted with checkpoint version = 3e684111
> FSTYP         -- f2fs
> PLATFORM      -- Linux/x86_64 sle15sp5 6.7.0-gf27274eae416 #8 SMP PREEMPT_DYNAMIC Thu Mar 14 00:22:47 CET 2024
> MKFS_OPTIONS  -- -O encrypt /dev/loop1
> MOUNT_OPTIONS -- -o acl,user_xattr /dev/loop1 /root/work/scratch
> 
> [   75.038385] F2FS-fs (loop1): Found nat_bits in checkpoint
> [   75.054311] F2FS-fs (loop1): Mounted with checkpoint version = 6b9fbccb
> [   75.176328] F2FS-fs (loop0): Using encoding defined by superblock: utf8-12.1.0 with flags 0x0
> [   75.179261] F2FS-fs (loop0): Found nat_bits in checkpoint
> [   75.194264] F2FS-fs (loop0): Mounted with checkpoint version = 3e684114
> f2fs/001 1s ... [   75.570867] run fstests f2fs/001 at 2024-03-14 00:24:33
> [   75.753604] BUG: unable to handle page fault for address: fffff14ad2000008
> [   75.754209] #PF: supervisor read access in kernel mode
> [   75.754647] #PF: error_code(0x0000) - not-present page
> [   75.755077] PGD 0 P4D 0 
> [   75.755300] Oops: 0000 [#1] PREEMPT SMP NOPTI
> [   75.755683] CPU: 0 PID: 2740 Comm: xfs_io Not tainted 6.7.0-gf27274eae416 #8
> [   75.756266] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 2/2/2022
> [   75.756911] RIP: 0010:kmem_cache_free+0x6a/0x320
> [   75.757309] Code: 80 48 01 d8 0f 82 b4 02 00 00 48 c7 c2 00 00 00 80 48 2b 15 f8 c2 18 01 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 03 05 d6 c2 18 01 <48> 8b 50 08 49 89 c6 f6 c2 01 0f 85 ea 01 00 00 0f 1f 44 00 00 49
> [   75.758834] RSP: 0018:ffffa59bc231bb10 EFLAGS: 00010286
> [   75.759270] RAX: fffff14ad2000000 RBX: 0000000000000000 RCX: 0000000000000000
> [   75.759860] RDX: 0000620400000000 RSI: 0000000000000000 RDI: ffff9dfc80043600
> [   75.760450] RBP: ffffa59bc231bb30 R08: ffffa59bc231b9a0 R09: 00000000000003fa
> [   75.761037] R10: 00000000000fd024 R11: 0000000000000107 R12: ffff9dfc80043600
> [   75.761626] R13: ffffffff8404dc7a R14: 0000000000000000 R15: ffff9dfc8f1aa000
> [   75.762221] FS:  00007f9601efb780(0000) GS:ffff9dfcfbc00000(0000) knlGS:0000000000000000
> [   75.762888] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   75.763372] CR2: fffff14ad2000008 CR3: 0000000111750000 CR4: 0000000000750ef0
> [   75.763962] PKRU: 55555554
> [   75.764194] Call Trace:
> [   75.764435]  <TASK>
> [   75.764677]  ? __die_body+0x1a/0x60
> [   75.764982]  ? page_fault_oops+0x154/0x440
> [   75.765335]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.765760]  ? search_module_extables+0x46/0x70
> [   75.766149]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.766548]  ? fixup_exception+0x22/0x300
> [   75.766892]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.767292]  ? exc_page_fault+0xa6/0x140
> [   75.767633]  ? asm_exc_page_fault+0x22/0x30
> [   75.767995]  ? f2fs_free_filename+0x2a/0x40
> [   75.768362]  ? kmem_cache_free+0x6a/0x320
> [   75.768703]  ? f2fs_free_filename+0x2a/0x40
> [   75.769061]  f2fs_free_filename+0x2a/0x40
> [   75.769403]  f2fs_lookup+0x19f/0x380
> [   75.769712]  __lookup_slow+0x8b/0x130
> [   75.770034]  walk_component+0xfc/0x170
> [   75.770353]  path_lookupat+0x69/0x140
> [   75.770664]  filename_lookup+0xe1/0x1c0
> [   75.770991]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.771393]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.771792]  ? do_wp_page+0x3f6/0xbf0
> [   75.772109]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.772523]  ? preempt_count_add+0x70/0xa0
> [   75.772902]  ? vfs_statx+0x89/0x180
> [   75.773224]  vfs_statx+0x89/0x180
> [   75.773530]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.773939]  vfs_fstatat+0x80/0xa0
> [   75.774237]  __do_sys_newfstatat+0x26/0x60
> [   75.774595]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.775021]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.775448]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.775878]  ? do_user_addr_fault+0x563/0x7c0
> [   75.776273]  ? srso_alias_return_thunk+0x5/0xfbef5
> [   75.776699]  do_syscall_64+0x50/0x110
> [   75.777028]  entry_SYSCALL_64_after_hwframe+0x6e/0x76
> [   75.777479] RIP: 0033:0x7f9601b07aea
> [   75.777793] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 01 23 0e 00 f7
> [   75.779391] RSP: 002b:00007ffc160eaae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
> [   75.780050] RAX: ffffffffffffffda RBX: 0000000000000042 RCX: 00007f9601b07aea
> [   75.780663] RDX: 00007ffc160eab80 RSI: 00007ffc160ecb88 RDI: 00000000ffffff9c
> [   75.781278] RBP: 00007ffc160ead20 R08: 00007ffc160ead20 R09: 0000000000000000
> [   75.781902] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc160eae70
> [   75.782532] R13: 00007ffc160ecb88 R14: 00007ffc160eae70 R15: 0000000000000020
> [   75.783150]  </TASK>
> [   75.783349] Modules linked in:
> [   75.783628] CR2: fffff14ad2000008
> [   75.783918] ---[ end trace 0000000000000000 ]---
> [   75.784315] RIP: 0010:kmem_cache_free+0x6a/0x320
> [   75.784718] Code: 80 48 01 d8 0f 82 b4 02 00 00 48 c7 c2 00 00 00 80 48 2b 15 f8 c2 18 01 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 03 05 d6 c2 18 01 <48> 8b 50 08 49 89 c6 f6 c2 01 0f 85 ea 01 00 00 0f 1f 44 00 00 49
> [   75.786294] RSP: 0018:ffffa59bc231bb10 EFLAGS: 00010286
> [   75.786747] RAX: fffff14ad2000000 RBX: 0000000000000000 RCX: 0000000000000000
> [   75.787369] RDX: 0000620400000000 RSI: 0000000000000000 RDI: ffff9dfc80043600
> [   75.788016] RBP: ffffa59bc231bb30 R08: ffffa59bc231b9a0 R09: 00000000000003fa
> [   75.788672] R10: 00000000000fd024 R11: 0000000000000107 R12: ffff9dfc80043600
> [   75.789296] R13: ffffffff8404dc7a R14: 0000000000000000 R15: ffff9dfc8f1aa000
> [   75.789938] FS:  00007f9601efb780(0000) GS:ffff9dfcfbc00000(0000) knlGS:0000000000000000
> [   75.790677] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   75.791212] CR2: fffff14ad2000008 CR3: 0000000111750000 CR4: 0000000000750ef0
> [   75.791862] PKRU: 55555554
> [   75.792112] Kernel panic - not syncing: Fatal exception
> [   75.792797] Kernel Offset: 0x2a00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
> 
>