diff options
| author | Cheng Jui Wang <cheng-jui.wang@mediatek.com> | 2022-02-10 18:50:11 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-02-23 12:01:08 +0100 |
| commit | 6062d1267ff3e5570165c974bb0dc2120c9d363c (patch) | |
| tree | f8c94ac725e40282fbeb46f24904d9898e4ba263 | |
| parent | f333c1916fd6b55900029bf8f918cc00009e2111 (diff) | |
lockdep: Correct lock_classes index mapping
commit 28df029d53a2fd80c1b8674d47895648ad26dcfb upstream.
A kernel exception was hit when trying to dump /proc/lockdep_chains after
lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!":
Unable to handle kernel paging request at virtual address 00054005450e05c3
...
00054005450e05c3] address between user and kernel address ranges
...
pc : [0xffffffece769b3a8] string+0x50/0x10c
lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c
...
Call trace:
string+0x50/0x10c
vsnprintf+0x468/0x69c
seq_printf+0x8c/0xd8
print_name+0x64/0xf4
lc_show+0xb8/0x128
seq_read_iter+0x3cc/0x5fc
proc_reg_read_iter+0xdc/0x1d4
The cause of the problem is the function lock_chain_get_class() will
shift lock_classes index by 1, but the index don't need to be shifted
anymore since commit 01bb6f0af992 ("locking/lockdep: Change the range
of class_idx in held_lock struct") already change the index to start
from 0.
The lock_classes[-1] located at chain_hlocks array. When printing
lock_classes[-1] after the chain_hlocks entries are modified, the
exception happened.
The output of lockdep_chains are incorrect due to this problem too.
Fixes: f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey")
Signed-off-by: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20220210105011.21712-1-cheng-jui.wang@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/locking/lockdep.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 1f6a2f1226fa..af4b35450556 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3387,7 +3387,7 @@ struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) u16 chain_hlock = chain_hlocks[chain->base + i]; unsigned int class_idx = chain_hlock_class_idx(chain_hlock); - return lock_classes + class_idx - 1; + return lock_classes + class_idx; } /* @@ -3455,7 +3455,7 @@ static void print_chain_keys_chain(struct lock_chain *chain) hlock_id = chain_hlocks[chain->base + i]; chain_key = print_chain_key_iteration(hlock_id, chain_key); - print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id) - 1); + print_lock_name(lock_classes + chain_hlock_class_idx(hlock_id)); printk("\n"); } } |