Hi -
I'm testing the NFSD support for attribute delegation, and seeing these
two new fstests failures: generic/647 and generic/729. Both tests emit
this error message:
mmap-rw-fault: pread /media/test/mmap-rw-fault.tmp (O_DIRECT): 0 !=
4096: Bad address
This is 100% reproducible with the new patches applied to the server,
and 100% not reproducible when they are not applied on the server.
The failure is due to pread64() (on the client) returning EFAULT. On
the wire, the passing test does:
SETATTR (size = 0)
WRITE (offset = 4096, len = 4096)
READ (offset = 0, len = 8192)
READ (offset = 4096, len = 4096)
SETATTR (size = 0)
[ continues until test passes ]
The failing test does:
SETATTR (size = 0)
WRITE (offset = 4096, len = 4096)
[ the failed pread64 seems to occur here ]
CLOSE
In other words, in the failing case, the client does not emit READs
to pull in the changed file content.
The test is using O_DIRECT so I function-traced
nfs_direct_read_schedule_iovec(). In the passing case, this function
generates the usual set of NFS READs on the wire and returns
successfully.
In the failing case, iov_iter_get_pages_alloc2() invokes
get_user_pages_fast(), and that appears to fail immediately:
mmap-rw-fault-623256 [016] 175303.310394: funcgraph_entry:
| get_user_pages_fast() {
mmap-rw-fault-623256 [016] 175303.310395: funcgraph_entry:
| gup_fast_fallback() {
mmap-rw-fault-623256 [016] 175303.310395: funcgraph_entry:
0.262 us | __pte_offset_map();
mmap-rw-fault-623256 [016] 175303.310395: funcgraph_entry:
0.142 us | __rcu_read_unlock();
mmap-rw-fault-623256 [016] 175303.310396: funcgraph_entry:
7.824 us | __gup_longterm_locked();
mmap-rw-fault-623256 [016] 175303.310404: funcgraph_exit:
8.967 us | }
mmap-rw-fault-623256 [016] 175303.310404: funcgraph_exit:
9.224 us | }
mmap-rw-fault-623256 [016] 175303.310404: funcgraph_entry:
| kvfree() {
My guess is the cached inode file size is still zero.
Any wisdom you can provide would be appreciated!
--
Chuck Lever
