In z_erofs_get_gbuf(), the current task may be migrated to another CPU between `z_erofs_gbuf_id()` and `spin_lock(&gbuf->lock)`.
Therefore, z_erofs_put_gbuf() will trigger the following issue which was found by stress test:
<2>[772156.434168] kernel BUG at fs/erofs/zutil.c:58! .. <4>[772156.435007] <4>[772156.439237] CPU: 0 PID: 3078 Comm: stress Kdump: loaded Tainted: G E 6.10.0-rc7+ #2 <4>[772156.439239] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 1.0.0 01/01/2017 <4>[772156.439241] pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) <4>[772156.439243] pc : z_erofs_put_gbuf+0x64/0x70 [erofs] <4>[772156.439252] lr : z_erofs_lz4_decompress+0x600/0x6a0 [erofs] .. <6>[772156.445958] stress (3127): drop_caches: 1 <4>[772156.446120] Call trace: <4>[772156.446121] z_erofs_put_gbuf+0x64/0x70 [erofs] <4>[772156.446761] z_erofs_lz4_decompress+0x600/0x6a0 [erofs] <4>[772156.446897] z_erofs_decompress_queue+0x740/0xa10 [erofs] <4>[772156.447036] z_erofs_runqueue+0x428/0x8c0 [erofs] <4>[772156.447160] z_erofs_readahead+0x224/0x390 [erofs] ..
Fixes: f36f3010f676 ("erofs: rename per-CPU buffers to global buffer pool and make it configurable") Cc: stable@vger.kernel.org # 6.10+ Cc: Chunhai Guo guochunhai@vivo.com Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com --- fs/erofs/zutil.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c index b80f612867c2..9b53883e5caf 100644 --- a/fs/erofs/zutil.c +++ b/fs/erofs/zutil.c @@ -38,11 +38,13 @@ void *z_erofs_get_gbuf(unsigned int requiredpages) { struct z_erofs_gbuf *gbuf;
+ migrate_disable(); gbuf = &z_erofs_gbufpool[z_erofs_gbuf_id()]; spin_lock(&gbuf->lock); /* check if the buffer is too small */ if (requiredpages > gbuf->nrpages) { spin_unlock(&gbuf->lock); + migrate_enable(); /* (for sparse checker) pretend gbuf->lock is still taken */ __acquire(gbuf->lock); return NULL; @@ -57,6 +59,7 @@ void z_erofs_put_gbuf(void *ptr) __releases(gbuf->lock) gbuf = &z_erofs_gbufpool[z_erofs_gbuf_id()]; DBG_BUGON(gbuf->ptr != ptr); spin_unlock(&gbuf->lock); + migrate_enable(); }
int z_erofs_gbuf_growsize(unsigned int nrpages)