mm/hugetlb_cgroup: prepare cftypes based on template

Unlike other cgroup subsystems, the hugetlb cgroup does not provide a
static array of cftype that explicitly displays the properties, handling
functions, etc., of each file.  Instead, it dynamically creates the
attribute of cftypes based on the hstate during the startup procedure. 
This reduces the readability of the code.

To fix this issue, introduce two templates of cftypes, and rebuild the
attributes according to the hstate to make it ready to be added to cgroup
framework.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Xiu Jianfeng <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: kernel test robot <[email protected]>
From: Xiu Jianfeng <[email protected]>
Subject: mm/hugetlb_cgroup: register lockdep key for cftype
Date: Tue, 18 Jun 2024 07:19:22 +0000

When CONFIG_DEBUG_LOCK_ALLOC is enabled, the following commands can
trigger a bug,

mount -t cgroup2 none /sys/fs/cgroup
cd /sys/fs/cgroup
echo "+hugetlb" > cgroup.subtree_control

The log is as below:

BUG: key ffff8880046d88d8 has not been registered!
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 3 PID: 226 at kernel/locking/lockdep.c:4945 lockdep_init_map_type+0x185/0x220
Modules linked in:
CPU: 3 PID: 226 Comm: bash Not tainted 6.10.0-rc4-next-20240617-g76db4c64526c #544
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:lockdep_init_map_type+0x185/0x220
Code: 00 85 c0 0f 84 6c ff ff ff 8b 3d 6a d1 85 01 85 ff 0f 85 5e ff ff ff 48 c7 c6 21 99 4a 82 48 c7 c7 60 29 49 82 e8 3b 2e f5
RSP: 0018:ffffc9000083fc30 EFLAGS: 00000282
RAX: 0000000000000000 RBX: ffffffff828dd820 RCX: 0000000000000027
RDX: ffff88803cd9cac8 RSI: 0000000000000001 RDI: ffff88803cd9cac0
RBP: ffff88800674fbb0 R08: ffffffff828ce248 R09: 00000000ffffefff
R10: ffffffff8285e260 R11: ffffffff828b8eb8 R12: ffff8880046d88d8
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880067281c0
FS:  00007f68601ea740(0000) GS:ffff88803cd80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005614f3ebc740 CR3: 000000000773a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ? __warn+0x77/0xd0
 ? lockdep_init_map_type+0x185/0x220
 ? report_bug+0x189/0x1a0
 ? handle_bug+0x3c/0x70
 ? exc_invalid_op+0x18/0x70
 ? asm_exc_invalid_op+0x1a/0x20
 ? lockdep_init_map_type+0x185/0x220
 __kernfs_create_file+0x79/0x100
 cgroup_addrm_files+0x163/0x380
 ? find_held_lock+0x2b/0x80
 ? find_held_lock+0x2b/0x80
 ? find_held_lock+0x2b/0x80
 css_populate_dir+0x73/0x180
 cgroup_apply_control_enable+0x12f/0x3a0
 cgroup_subtree_control_write+0x30b/0x440
 kernfs_fop_write_iter+0x13a/0x1f0
 vfs_write+0x341/0x450
 ksys_write+0x64/0xe0
 do_syscall_64+0x4b/0x110
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f68602d9833
Code: 8b 15 61 26 0e 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 08
RSP: 002b:00007fff9bbdf8e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f68602d9833
RDX: 0000000000000009 RSI: 00005614f3ebc740 RDI: 0000000000000001
RBP: 00005614f3ebc740 R08: 000000000000000a R09: 0000000000000008
R10: 00005614f3db6ba0 R11: 0000000000000246 R12: 0000000000000009
R13: 00007f68603bd6a0 R14: 0000000000000009 R15: 00007f68603b8880

For lockdep, there is a sanity check in lockdep_init_map_type(), the
lock-class key must either have been allocated statically or must
have been registered as a dynamic key. However the commit e18df2889ff9
("mm/hugetlb_cgroup: prepare cftypes based on template") has changed
the cftypes from static allocated objects to dynamic allocated objects,
so the cft->lockdep_key must be registered proactively.

[[email protected]: fix BUG()]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lore.kernel.org/all/[email protected]/
Fixes: e18df2889ff9 ("mm/hugetlb_cgroup: prepare cftypes based on template")
Signed-off-by: Xiu Jianfeng <[email protected]>
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Tested-by: Marek Szyprowski <[email protected]>
Tested-by: SeongJae Park <[email protected]>
Closes: https://lore.kernel.org/[email protected]
Cc: Muchun Song <[email protected]>
Cc: Oscar Salvador <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 0 insertions, 2 deletions

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index ea48c861cd36..dc151cb0ef09 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -676,9 +676,7 @@ struct cftype {
 	__poll_t (*poll)(struct kernfs_open_file *of,
 			 struct poll_table_struct *pt);
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lock_class_key	lockdep_key;
-#endif
 };
 
 /*