On 01/20/2014 10:02 PM, Matias Bjorling wrote:
On 01/20/2014 04:58 AM, Raghavendra K T wrote:
If we load the null_blk module with bs=8k we get following oops:
[ 3819.812190] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 3819.812387] IP: [<ffffffff81170aa5>] create_empty_buffers+0x28/0xaf
[ 3819.812527] PGD 219244067 PUD 215a06067 PMD 0
[ 3819.812640] Oops: 0000 [#1] SMP
[ 3819.812772] Modules linked in: null_blk(+)
Fix that by resetting block size to PAGE_SIZE if it is greater than PAGE_SIZE
Also add sanity checks for block size > PAGE_SIZE.
We should probably split the patch into two. Giving a better description
to each of the changes.
Agreed.
[...]
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index a2e69d2..bcae726 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -622,6 +622,10 @@ static int __init null_init(void)
irqmode = NULL_IRQ_NONE;
}
#endif
+ if (bs > PAGE_SIZE) {
+ pr_warn("Invalid block size. Setting it to %lu\n", PAGE_SIZE);
+ bs = PAGE_SIZE;
+ }
Could the warning say something like:
pr_warn("null_blk: invalid block size\n");
pr_warn("null_blk: defaults block size to &lu\n");
then it follows the same patterns as the other errors.
Agree.
if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
if (submit_queues < nr_online_nodes) {
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 1e86823..2481d42 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1027,6 +1027,7 @@ void bd_set_size(struct block_device *bdev, loff_t size)
break;
bsize <<= 1;
}
+ BUG_ON(bsize > PAGE_SIZE);
bdev->bd_block_size = bsize;
bdev->bd_inode->i_blkbits = blksize_bits(bsize);
}
diff --git a/fs/buffer.c b/fs/buffer.c
index 6024877..8b7ada1 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1571,6 +1571,7 @@ void create_empty_buffers(struct page *page,
struct buffer_head *bh, *head, *tail;
head = alloc_page_buffers(page, blocksize, 1);
+ BUG_ON(!head);
bh = head;
do {
bh->b_state |= b_state;
For the check patch, the description could mention some text on why we
hit this error case and why we check for it.
Thanks for the suggestions. Will post V3 with the changes.
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