linux-kernel - Re: [PATCH] slab: Error out on duplicate cache names when DEBUG

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Message-ID: <CAKbZUD0hBFeMm=Rwb1LX6MYEpLK_qAnr8jfczLzY8V-DKEDn4w@mail.gmail.com>
Date: Mon, 5 Aug 2024 11:24:40 +0100
From: Pedro Falcato <pedro.falcato@...il.com>
To: Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>, 
	David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka <vbabka@...e.cz>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>, Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] slab: Error out on duplicate cache names when DEBUG_VM=y

On Sun, Aug 4, 2024 at 10:28 PM Pedro Falcato <pedro.falcato@...il.com> wrote:
>
> Duplicate slab cache names can create havoc for userspace tooling that
> expects slab cache names to be unique. This is a reasonable expectation.

For completeness, I just had a look at duplicate cache names around
the kernel using
git grep -Eoh "kmem_cache_create.*\"," | grep -Eo \".*\" | uniq -d
(which seems to be correct)

which results in the following patch (on top of torvalds/linux.git
master, so file_lock_cache hasn't been fixed yet)

This patch being so small is what leads me to believe that erroring
out here is safe. Of course, no one knows what the out-of-tree modules
do.

diff --git a/drivers/scsi/snic/snic_main.c b/drivers/scsi/snic/snic_main.c
index cc824dcfe7d..abc78320c66 100644
--- a/drivers/scsi/snic/snic_main.c
+++ b/drivers/scsi/snic/snic_main.c
@@ -873,7 +873,7 @@ snic_global_data_init(void)
       snic_glob->req_cache[SNIC_REQ_CACHE_MAX_SGL] = cachep;

       len = sizeof(struct snic_host_req);
-       cachep = kmem_cache_create("snic_req_maxsgl", len, SNIC_SG_DESC_ALIGN,
+       cachep = kmem_cache_create("snic_req_tm", len, SNIC_SG_DESC_ALIGN,
                                  SLAB_HWCACHE_ALIGN, NULL);
       if (!cachep) {
               SNIC_ERR("Failed to create snic tm req slab\n");
diff --git a/fs/locks.c b/fs/locks.c
index 9afb16e0683..e45cad40f8b 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2984,7 +2984,7 @@ static int __init filelock_init(void)
       filelock_cache = kmem_cache_create("file_lock_cache",
                       sizeof(struct file_lock), 0, SLAB_PANIC, NULL);

-       filelease_cache = kmem_cache_create("file_lock_cache",
+       filelease_cache = kmem_cache_create("file_lease_cache",
                       sizeof(struct file_lease), 0, SLAB_PANIC, NULL);

       for_each_possible_cpu(i) {