linux-kernel - Re: mempool_alloc_bulk and various mempool improvements v3

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Message-ID: <f58a2fcb-2306-4c27-a20c-11ac953c1b5d@suse.cz>
Date: Thu, 13 Nov 2025 17:12:18 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Christoph Hellwig <hch@....de>, Andrew Morton <akpm@...ux-foundation.org>
Cc: Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>,
 Roman Gushchin <roman.gushchin@...ux.dev>, Harry Yoo <harry.yoo@...cle.com>,
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
 Brendan Jackman <jackmanb@...gle.com>, Zi Yan <ziy@...dia.com>,
 Eric Biggers <ebiggers@...nel.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: mempool_alloc_bulk and various mempool improvements v3

On 11/13/25 09:39, Christoph Hellwig wrote:
> Hi all,
> 
> this series adds a bulk version of mempool_alloc that makes allocating
> multiple objects deadlock safe.
> 
> The initial users is the blk-crypto-fallback code:
> 
>   https://lore.kernel.org/linux-block/20251031093517.1603379-1-hch@lst.de/
> 
> with which v1 was posted, but I also have a few other users in mind.
> 
> Changes since v2:
>  - improve the alloc_pages_bulk documentation a bit
>  - drop the not needed race fix again
>  - drop the gfp_mask argument to mempool_alloc_bulk to reduce misuse
>    potential
>  - add an allocated argument to mempool_alloc_bulk
>  - drop the caller_ip handling that was already not required since the
>    last version
>  - add a few more mempool cleanups

LGTM now.
Since mempool is now part of SLAB in MAINTAINERS, added to slab/for-next.
Thanks!
> Changes since v1:
>  - fix build for !CONFIG_FAULT_INJECTION
>  - improve the kerneldoc comments further
>  - refactor the code so that the mempool_alloc fastpath does not
>    have to deal with arrays
>  - don't support !__GFP_DIRECT_RECLAIM for bulk allocations
>  - do poll allocations even if not all elements are available
>  - s/elem/elems/
>  - use a separate failure injection know for the bulk allocator
> 
> diffstat:
>  include/linux/fault-inject.h |    8 
>  include/linux/mempool.h      |   58 ++----
>  mm/mempool.c                 |  401 ++++++++++++++++++++++++++-----------------
>  mm/page_alloc.c              |   15 +
>  4 files changed, 289 insertions(+), 193 deletions(-)