On Mon, 2019-03-18 at 17:00 +0000, Catalin Marinas wrote:
Commit 7b587e1a5a6c ("NFS: use locks_copy_lock() to copy locks.") changed the lock copying from memcpy() to the dedicated locks_copy_lock() function. The latter correctly increments the nfs4_lock_state.ls_count via nfs4_fl_copy_lock(), however, this refcount has already been incremented in the nfs4_alloc_{lock,unlock}data(). Kmemleak subsequently reports an unreferenced nfs4_lock_state object as below (arm64 platform):
unreferenced object 0xffff8000fce0b000 (size 256): comm "systemd-sysuser", pid 1608, jiffies 4294892825 (age 32.348s) hex dump (first 32 bytes): 20 57 4c fb 00 80 ff ff 20 57 4c fb 00 80 ff ff WL..... WL..... 00 57 4c fb 00 80 ff ff 01 00 00 00 00 00 00 00 .WL............. backtrace: [<000000000d15010d>] kmem_cache_alloc+0x178/0x208 [<00000000d7c1d264>] nfs4_set_lock_state+0x124/0x1f0 [<000000009c867628>] nfs4_proc_lock+0x90/0x478 [<000000001686bd74>] do_setlk+0x64/0xe8 [<00000000e01500d4>] nfs_lock+0xe8/0x1f0 [<000000004f387d8d>] vfs_lock_file+0x18/0x40 [<00000000656ab79b>] do_lock_file_wait+0x68/0xf8 [<00000000f17c4a4b>] fcntl_setlk+0x224/0x280 [<0000000052a242c6>] do_fcntl+0x418/0x730 [<000000004f47291a>] __arm64_sys_fcntl+0x84/0xd0 [<00000000d6856e01>] el0_svc_common+0x80/0xf0 [<000000009c4bd1df>] el0_svc_handler+0x2c/0x80 [<00000000b1a0d479>] el0_svc+0x8/0xc [<0000000056c62a0f>] 0xffffffffffffffff
This patch removes the original refcount_inc(&lsp->ls_count) that was paired with the memcpy() lock copying.
Fixes: 7b587e1a5a6c ("NFS: use locks_copy_lock() to copy locks.") Cc: stable@vger.kernel.org # 5.0.x- Cc: NeilBrown neilb@suse.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com
fs/nfs/nfs4proc.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 4dbb0ee23432..6d2812a39287 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -6301,7 +6301,6 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl, p->arg.seqid = seqid; p->res.seqid = seqid; p->lsp = lsp;
- refcount_inc(&lsp->ls_count); /* Ensure we don't close file until we're done freeing locks!
*/ p->ctx = get_nfs_open_context(ctx); p->l_ctx = nfs_get_lock_context(ctx); @@ -6526,7 +6525,6 @@ static struct nfs4_lockdata *nfs4_alloc_lockdata(struct file_lock *fl, p->res.lock_seqid = p->arg.lock_seqid; p->lsp = lsp; p->server = server;
- refcount_inc(&lsp->ls_count); p->ctx = get_nfs_open_context(ctx); locks_init_lock(&p->fl); locks_copy_lock(&p->fl, fl);
Thanks Catalin! Good catch...
I'm applying this to my linux-next branch.