linux-kernel - Re: [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak objects

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190730130215.919b31c19df935cc5f1483e6@linux-foundation.org>
Date:   Tue, 30 Jul 2019 13:02:15 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Catalin Marinas <catalin.marinas@....com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Michal Hocko <mhocko@...nel.org>,
        Matthew Wilcox <willy@...radead.org>, Qian Cai <cai@....pw>
Subject: Re: [PATCH v2] mm: kmemleak: Use mempool allocations for kmemleak
 objects

On Sat, 27 Jul 2019 14:23:33 +0100 Catalin Marinas <catalin.marinas@....com> wrote:

> Add mempool allocations for struct kmemleak_object and
> kmemleak_scan_area as slightly more resilient than kmem_cache_alloc()
> under memory pressure. Additionally, mask out all the gfp flags passed
> to kmemleak other than GFP_KERNEL|GFP_ATOMIC.
> 
> A boot-time tuning parameter (kmemleak.mempool) is added to allow a
> different minimum pool size (defaulting to NR_CPUS * 4).

btw, the checkpatch warnings are valid:

WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc
#70: FILE: mm/kmemleak.c:197:
+static int min_object_pool = NR_CPUS * 4;

WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc
#71: FILE: mm/kmemleak.c:198:
+static int min_scan_area_pool = NR_CPUS * 1;

There can be situations where NR_CPUS is much larger than
num_possible_cpus().  Can we initialize these tunables within
kmemleak_init()?