Suppress large kmem_alloc() warning

The following warning was observed under normal operation.  It's
not fatal but it's something to be addressed long term.  Flag the
offending allocation with KM_NODEBUG to suppress the warning and
flag the call site.

SPL: Showing stack for process 21761
Pid: 21761, comm: iozone Tainted: P           ----------------
2.6.32-71.14.1.el6.x86_64 #1
Call Trace:
 [<ffffffffa05465a7>] spl_debug_dumpstack+0x27/0x40 [spl]
 [<ffffffffa054a84d>] kmem_alloc_debug+0x11d/0x130 [spl]
 [<ffffffffa05de166>] dmu_buf_hold_array_by_dnode+0xa6/0x4e0 [zfs]
 [<ffffffffa05de825>] dmu_buf_hold_array+0x65/0x90 [zfs]
 [<ffffffffa05de891>] dmu_read_uio+0x41/0xd0 [zfs]
 [<ffffffffa0654827>] zfs_read+0x147/0x470 [zfs]
 [<ffffffffa06644a2>] zpl_read_common+0x52/0x70 [zfs]
 [<ffffffffa0664503>] zpl_read+0x43/0x70 [zfs]
 [<ffffffff8116d905>] vfs_read+0xb5/0x1a0
 [<ffffffff8116da41>] sys_read+0x51/0x90
 [<ffffffff81013172>] system_call_fastpath+0x16/0x1b

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index ede0d0517617f3fc86737dd4415a2e5a00a556bf..04b02c7d22cb876cac28350176e795d9661d2dba 100644 (file)
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -381,7 +381,7 @@ dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
                }
                nblks = 1;
        }
-       dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
+       dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP | KM_NODEBUG);
 
        if (dn->dn_objset->os_dsl_dataset)
                dp = dn->dn_objset->os_dsl_dataset->ds_dir->dd_pool;