Re: 5.3-rc1 regression with XFS log recovery

hch
2019-08-18T17:34:31Z

On Sun, Aug 18, 2019 at 09:41:40AM +0200, hch@lst.de wrote:
> On Sun, Aug 18, 2019 at 09:11:28AM +0200, hch@lst.de wrote:
> > > The kernel log shows the following when the mount fails:
> >
> > Is it always that same message? I'll see if I can reproduce it,
> > but I won't have that much memory to spare to create fake pmem,
> > hope this also works with a single device and/or less memory..
>
> I've reproduced a similar ASSERT with a small pmem device, so I hope
> I can debug the issue locally now.

So I can also reproduce the same issue with the ramdisk driver, but not
with any other 4k sector size device (nvmet, scsi target, scsi_debug,
loop). Which made me wonder if there is some issue about the memory
passed in, and indeed just switching to plain vmalloc vs the XFS
kmem_alloc_large wrapper that either uses kmalloc or vmalloc fixes
the issue for me. I don't really understand why yet, maybe I need to
dig out alignment testing patches.

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 13d1d3e95b88..918ad3b884a7 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -125,7 +125,7 @@ xlog_alloc_buffer(
if (nbblks > 1 && log->l_sectBBsize > 1)
nbblks += log->l_sectBBsize;
nbblks = round_up(nbblks, log->l_sectBBsize);
- return kmem_alloc_large(BBTOB(nbblks), KM_MAYFAIL);
+ return vmalloc(BBTOB(nbblks));
}

/*
@@ -416,7 +416,7 @@ xlog_find_verify_cycle(
*new_blk = -1;

out:
- kmem_free(buffer);
+ vfree(buffer);
return error;
}

@@ -527,7 +527,7 @@ xlog_find_verify_log_record(
*last_blk = i;

out:
- kmem_free(buffer);
+ vfree(buffer);
return error;
}

@@ -781,7 +781,7 @@ xlog_find_head(
goto out_free_buffer;
}

- kmem_free(buffer);
+ vfree(buffer);
if (head_blk == log_bbnum)
*return_head_blk = 0;
else
@@ -795,7 +795,7 @@ xlog_find_head(
return 0;

out_free_buffer:
- kmem_free(buffer);
+ vfree(buffer);
if (error)
xfs_warn(log->l_mp, "failed to find log head");
return error;
@@ -1049,7 +1049,7 @@ xlog_verify_tail(
"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
orig_tail, *tail_blk);
out:
- kmem_free(buffer);
+ vfree(buffer);
return error;
}

@@ -1096,7 +1096,7 @@ xlog_verify_head(
error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
XLOG_MAX_ICLOGS, tmp_buffer,
&tmp_rhead_blk, &tmp_rhead, &tmp_wrapped);
- kmem_free(tmp_buffer);
+ vfree(tmp_buffer);
if (error < 0)
return error;

@@ -1429,7 +1429,7 @@ xlog_find_tail(
error = xlog_clear_stale_blocks(log, tail_lsn);

done:
- kmem_free(buffer);
+ vfree(buffer);

if (error)
xfs_warn(log->l_mp, "failed to locate log tail");
@@ -1477,7 +1477,7 @@ xlog_find_zeroed(
first_cycle = xlog_get_cycle(offset);
if (first_cycle == 0) { /* completely zeroed log */
*blk_no = 0;
- kmem_free(buffer);
+ vfree(buffer);
return 1;
}

@@ -1488,7 +1488,7 @@ xlog_find_zeroed(

last_cycle = xlog_get_cycle(offset);
if (last_cycle != 0) { /* log completely written to */
- kmem_free(buffer);
+ vfree(buffer);
return 0;
}

@@ -1535,7 +1535,7 @@ xlog_find_zeroed(

*blk_no = last_blk;
out_free_buffer:
- kmem_free(buffer);
+ vfree(buffer);
if (error)
return error;
return 1;
@@ -1647,7 +1647,7 @@ xlog_write_log_records(
}

out_free_buffer:
- kmem_free(buffer);
+ vfree(buffer);
return error;
}

@@ -5291,7 +5291,7 @@ xlog_do_recovery_pass(
hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
if (h_size % XLOG_HEADER_CYCLE_SIZE)
hblks++;
- kmem_free(hbp);
+ vfree(hbp);
hbp = xlog_alloc_buffer(log, hblks);
} else {
hblks = 1;
@@ -5307,7 +5307,7 @@ xlog_do_recovery_pass(
return -ENOMEM;
dbp = xlog_alloc_buffer(log, BTOBB(h_size));
if (!dbp) {
- kmem_free(hbp);
+ vfree(hbp);
return -ENOMEM;
}

@@ -5468,9 +5468,9 @@ xlog_do_recovery_pass(
}

bread_err2:
- kmem_free(dbp);
+ vfree(dbp);
bread_err1:
- kmem_free(hbp);
+ vfree(hbp);

/*
* Submit buffers that have been added from the last record processed,