From: Vlastimil Babka <vbabka@suse.cz>
To: "Christoph Lameter (Ampere)" <cl@gentwo.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Harry Yoo <harry.yoo@oracle.com>,
linux-mm@kvack.org
Subject: Re: [PATCH v2 04/22] slab: Remove dead code in free_consistency_checks()
Date: Thu, 11 Sep 2025 17:29:34 +0200 [thread overview]
Message-ID: <21321a30-4a4c-4d7e-a21b-089ae38eec35@suse.cz> (raw)
In-Reply-To: <4109cf0b-bd09-115f-5c84-58a8b9fe19de@gentwo.org>
On 9/11/25 00:30, Christoph Lameter (Ampere) wrote:
> On Wed, 10 Sep 2025, Matthew Wilcox (Oracle) wrote:
>
>> We already know that slab is a valid slab as that's checked by the
>> caller. In the future, we won't be able to get to a slab pointer
>> from a non-slab page.
>
> No we dont. This is another case where there is a metadata mismatch and
> where we already know that something is wrong.
It's been already checked by free_debug_processing() doing check_slab().
> s should be equal to slab->slab_cache and it is not.
It's possible even this check is dead code because we got s from
slab->slab_cache somewhere before coming here.
It makes little sense to recheck everything over and over.
> Therefore we should diagnose if this is an actual slab before
> doing further diagnostics.
next prev parent reply other threads:[~2025-09-11 15:29 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-10 11:54 [PATCH v2 00/22] Prepare slab for memdescs Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 01/22] slab: Remove unnecessary test from alloc_debug_processing() Matthew Wilcox (Oracle)
2025-09-10 22:19 ` Christoph Lameter (Ampere)
2025-09-10 11:54 ` [PATCH v2 02/22] slab: Remove unnecessary test from alloc_single_from_partial() Matthew Wilcox (Oracle)
2025-09-10 22:23 ` Christoph Lameter (Ampere)
2025-09-11 16:38 ` Vlastimil Babka
2025-09-10 11:54 ` [PATCH v2 03/22] slab: Remove dead code in check_slab() Matthew Wilcox (Oracle)
2025-09-10 22:27 ` Christoph Lameter (Ampere)
2025-09-10 11:54 ` [PATCH v2 04/22] slab: Remove dead code in free_consistency_checks() Matthew Wilcox (Oracle)
2025-09-10 22:30 ` Christoph Lameter (Ampere)
2025-09-11 15:29 ` Vlastimil Babka [this message]
2025-09-10 11:54 ` [PATCH v2 05/22] mm: Constify compound_order() and page_size() Matthew Wilcox (Oracle)
2025-09-10 14:01 ` Vlastimil Babka
2025-09-10 17:33 ` Christoph Lameter (Ampere)
2025-09-10 11:54 ` [PATCH v2 06/22] slab: Reimplement page_slab() Matthew Wilcox (Oracle)
2025-09-10 22:46 ` Christoph Lameter (Ampere)
2025-09-10 23:01 ` Matthew Wilcox
2025-09-10 23:14 ` Christoph Lameter (Ampere)
2025-09-11 7:10 ` Vlastimil Babka
2025-09-11 11:35 ` Matthew Wilcox
2025-09-10 11:54 ` [PATCH v2 07/22] slab: Remove folio references from __ksize() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 08/22] slab: Remove folio references in memcg_slab_post_charge() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 09/22] slab: Remove folio references in slab alloc/free Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 10/22] slab: Remove folio references from ___kmalloc_large_node() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 11/22] slab: Remove folio references from free_large_kmalloc() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 12/22] slab: Remove folio references from kvfree_rcu_cb() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 13/22] slab: Remove folio references from kvfree() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 14/22] slab: Remove folio references from __do_krealloc() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 15/22] slab: Remove folio references from build_detached_freelist() Matthew Wilcox (Oracle)
2025-09-10 11:54 ` [PATCH v2 16/22] slab: Remove dead code from free_large_kmalloc() Matthew Wilcox (Oracle)
2025-09-10 22:45 ` Christoph Lameter (Ampere)
2025-09-10 11:54 ` [PATCH v2 17/22] slab: Remove folio references from kfree_rcu_sheaf() Matthew Wilcox (Oracle)
2025-09-10 11:55 ` [PATCH v2 18/22] usercopy: Remove folio references from check_heap_object() Matthew Wilcox (Oracle)
2025-09-10 11:55 ` [PATCH v2 19/22] memcg: Convert mem_cgroup_from_obj_folio() to mem_cgroup_from_obj_slab() Matthew Wilcox (Oracle)
2025-09-10 11:55 ` [PATCH v2 20/22] kasan: Remove references to folio in __kasan_mempool_poison_object() Matthew Wilcox (Oracle)
2025-09-10 11:55 ` [PATCH v2 21/22] slab: Remove references to folios from virt_to_slab() Matthew Wilcox (Oracle)
2025-09-10 11:55 ` [PATCH v2 22/22] mm: Remove redundant test in validate_page_before_insert() Matthew Wilcox (Oracle)
2025-09-10 14:02 ` Vlastimil Babka
2025-09-10 14:05 ` [PATCH v2 00/22] Prepare slab for memdescs Vlastimil Babka
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