The commit 4c39529663b9 adds a warning about duplicate cache names if
CONFIG_DEBUG_VM is selected. These warnings are triggered by the dm-bufio
code. The dm-bufio code allocates a slab cache with each client. It is
not possible to preallocate the caches in the module init function
because the size of auxiliary per-buffer data is not known at this point.
So, this commit changes dm-bufio so that it appends a unique atomic value
to the cache name, to avoid the warnings.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Fixes: 4c39529663b9 ("slab: Warn on duplicate cache names when DEBUG_VM=y")
---
drivers/md/dm-bufio.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
Index: linux-2.6/drivers/md/dm-bufio.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-bufio.c 2024-10-16 16:41:33.000000000 +0200
+++ linux-2.6/drivers/md/dm-bufio.c 2024-11-07 12:56:24.000000000 +0100
@@ -2471,7 +2471,8 @@ struct dm_bufio_client *dm_bufio_client_
int r;
unsigned int num_locks;
struct dm_bufio_client *c;
- char slab_name[27];
+ char slab_name[64];
+ static atomic_t seqno = ATOMIC_INIT(0);
if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) {
DMERR("%s: block size not specified or is not multiple of 512b", __func__);
@@ -2522,7 +2523,8 @@ struct dm_bufio_client *dm_bufio_client_
(block_size < PAGE_SIZE || !is_power_of_2(block_size))) {
unsigned int align = min(1U << __ffs(block_size), (unsigned int)PAGE_SIZE);
- snprintf(slab_name, sizeof(slab_name), "dm_bufio_cache-%u", block_size);
+ snprintf(slab_name, sizeof(slab_name), "dm_bufio_cache-%u-%u",
+ block_size, atomic_inc_return(&seqno));
c->slab_cache = kmem_cache_create(slab_name, block_size, align,
SLAB_RECLAIM_ACCOUNT, NULL);
if (!c->slab_cache) {
@@ -2531,9 +2533,11 @@ struct dm_bufio_client *dm_bufio_client_
}
}
if (aux_size)
- snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer-%u", aux_size);
+ snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer-%u-%u",
+ aux_size, atomic_inc_return(&seqno));
else
- snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer");
+ snprintf(slab_name, sizeof(slab_name), "dm_bufio_buffer-%u",
+ atomic_inc_return(&seqno));
c->slab_buffer = kmem_cache_create(slab_name, sizeof(struct dm_buffer) + aux_size,
0, SLAB_RECLAIM_ACCOUNT, NULL);
if (!c->slab_buffer) {
