* Re: 2.5.41 - kernel NULL pointer
2002-10-10 22:54 2.5.41 - kernel NULL pointer Cliff White
@ 2002-10-10 23:03 ` Andrew Morton
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2002-10-10 23:03 UTC (permalink / raw)
To: Cliff White; +Cc: linux-kernel
Cliff White wrote:
>
> System is 2-CPU PIII
> Attempting to start the SAP DB. Get this msg:
> SAP cannot open the sys devspace (which is on filesystem)
> DB setup does include one raw partition.
> Further details upon request
> cliffw
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> ...
> [<c01711a9>] generic_file_direct_IO+0x59/0x73
The raw driver was broken by the NFS direct IO merge. It's
unbroken in Linus' current tree. And some additional fixes
are needed on top of that.
--- 2.5.41/fs/direct-io.c~dio-bio-add-fix-1 Thu Oct 10 15:21:51 2002
+++ 2.5.41-akpm/fs/direct-io.c Thu Oct 10 15:52:50 2002
@@ -388,7 +388,7 @@ static void dio_prep_bio(struct dio *dio
/*
* There is no bio. Make one now.
*/
-static int dio_new_bio(struct dio *dio)
+static int dio_new_bio(struct dio *dio, sector_t blkno)
{
sector_t sector;
int ret, nr_pages;
@@ -396,7 +396,7 @@ static int dio_new_bio(struct dio *dio)
ret = dio_bio_reap(dio);
if (ret)
goto out;
- sector = dio->next_block_in_bio << (dio->blkbits - 9);
+ sector = blkno << (dio->blkbits - 9);
nr_pages = min(dio->pages_left, bio_get_nr_vecs(dio->map_bh.b_bdev));
BUG_ON(nr_pages <= 0);
ret = dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages);
@@ -408,22 +408,28 @@ out:
static int
dio_bio_add_page(struct dio *dio, struct page *page,
- unsigned int bv_len, unsigned int bv_offset)
+ unsigned int bv_len, unsigned int bv_offset, sector_t blkno)
{
int ret = 0;
if (bv_len == 0)
goto out;
+ /* Take a ref against the page each time it is placed into a BIO */
page_cache_get(page);
if (bio_add_page(dio->bio, page, bv_len, bv_offset)) {
dio_bio_submit(dio);
- ret = dio_new_bio(dio);
+ ret = dio_new_bio(dio, blkno);
if (ret == 0) {
ret = bio_add_page(dio->bio, page, bv_len, bv_offset);
BUG_ON(ret != 0);
+ } else {
+ /* The page didn't make it into a BIO */
+ page_cache_release(page);
}
}
+
+ /* Drop the ref which was taken in get_user_pages() */
page_cache_release(page);
dio->pages_left--;
out:
@@ -460,6 +466,7 @@ int do_direct_IO(struct dio *dio)
int new_page; /* Need to insert this page into the BIO? */
unsigned int bv_offset;
unsigned int bv_len;
+ sector_t curr_blkno;
page = dio_get_page(dio);
if (IS_ERR(page)) {
@@ -470,6 +477,7 @@ int do_direct_IO(struct dio *dio)
new_page = 1;
bv_offset = 0;
bv_len = 0;
+ curr_blkno = 0;
while (block_in_page < blocks_per_page) {
unsigned this_chunk_bytes; /* # of bytes mapped */
unsigned this_chunk_blocks; /* # of blocks */
@@ -494,7 +502,7 @@ int do_direct_IO(struct dio *dio)
dio_prep_bio(dio);
if (dio->bio == NULL) {
- ret = dio_new_bio(dio);
+ ret = dio_new_bio(dio, dio->next_block_in_bio);
if (ret)
goto out;
new_page = 1;
@@ -503,6 +511,7 @@ int do_direct_IO(struct dio *dio)
if (new_page) {
bv_len = 0;
bv_offset = block_in_page << blkbits;
+ curr_blkno = dio->next_block_in_bio;
new_page = 0;
}
@@ -530,7 +539,7 @@ next_block:
if (dio->block_in_file == dio->final_block_in_request)
break;
}
- ret = dio_bio_add_page(dio, page, bv_len, bv_offset);
+ ret = dio_bio_add_page(dio, page, bv_len, bv_offset, curr_blkno);
if (ret)
goto out;
block_in_page = 0;
.
^ permalink raw reply [flat|nested] 2+ messages in thread