On Mon, 27 Apr 2009 13:36:46 -0700 (PDT)
David Rientjes <rientjes@xxxxxxxxxx> wrote:
On Mon, 27 Apr 2009, Bart wrote:
After turning the suggested debuging options I've got tons of these when
trying to stress the tape device like before:
Apr 27 16:57:30 fs kernel: [ 96.446708] slab error in verify_redzone_free():
cache `size-128': memory outside object was overwritten
Apr 27 16:57:30 fs kernel: [ 96.446713] Pid: 0, comm: swapper Not tainted
2.6.29.1-64 #2
Apr 27 16:57:30 fs kernel: [ 96.446715] Call Trace:
Apr 27 16:57:30 fs kernel: [ 96.446717] <IRQ> [<ffffffff8029adc5>]
__slab_error+0x1f/0x25
Apr 27 16:57:30 fs kernel: [ 96.446728] [<ffffffff8029b24b>]
cache_free_debugcheck+0x108/0x1d6
Apr 27 16:57:30 fs kernel: [ 96.446731] [<ffffffff8029b473>]
kfree+0x81/0xc2
Apr 27 16:57:30 fs kernel: [ 96.446735] [<ffffffff802bd311>]
bio_free_map_data+0xc/0x1e
This appears to be kfree(bmd->iovecs) in bio_free_map_data(). It looks
like the memcpy size in bio_set_map_data() overrides the kmalloc size; in
other words, for a redzone error, bio->bi_vcnt > nr_pages in
bio_copy_user_iov().
Can you try this?
diff --git a/fs/bio.c b/fs/bio.c
index 7bbc98f..6a09356 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -817,6 +817,9 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
len += iov[i].iov_len;
}
+ if (offset)
+ nr_pages += 1;
+
bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
if (!bmd)
return ERR_PTR(-ENOMEM);
There are no more errors in the dmesg after applying this patch to
2.6.29.2.
Without this patch I can reproduce this kind of errors on
2.6.29.1, 2.6.29.2.
I've not tested this patch with 2.6.29.1 and 2.6.30rc3-git3.
I will try to reproduce the error on 2.6.30rc3-git3 as soon as I compile
it.
--
Regards
Bart mmx@xxxxxx
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