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From: Eric Biggers <ebiggers@kernel.org>
To: linux-block@vger.kernel.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	Vlastimil Babka <vbabka@kernel.org>, Harry Yoo <harry@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hao Li <hao.li@linux.dev>, Christoph Lameter <cl@gentwo.org>,
	David Rientjes <rientjes@google.com>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Eric Biggers <ebiggers@kernel.org>
Subject: [PATCH 1/3] mm: make mempool_alloc_from_pool() return bool
Date: Thu,  6 Aug 2026 15:10:29 -0700	[thread overview]
Message-ID: <20260806221031.79050-2-ebiggers@kernel.org> (raw)
In-Reply-To: <20260806221031.79050-1-ebiggers@kernel.org>

mempool_alloc_from_pool() is intentionally all-or-nothing, so make it
return a bool rather than the number of elements allocated.

Then make mempool_alloc_bulk() return right away if
mempool_alloc_from_pool() succeeds, rather than jumping back to the
retry_alloc label to allocate nothing and then returning.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 mm/mempool.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/mempool.c b/mm/mempool.c
index 473a029fa31f..d454bc9f39e9 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -409,7 +409,7 @@ int mempool_resize(struct mempool *pool, int new_min_nr)
 }
 EXPORT_SYMBOL(mempool_resize);
 
-static unsigned int mempool_alloc_from_pool(struct mempool *pool, void **elems,
+static bool mempool_alloc_from_pool(struct mempool *pool, void **elems,
 		unsigned int count, unsigned int allocated,
 		gfp_t gfp_mask)
 {
@@ -432,7 +432,7 @@ static unsigned int mempool_alloc_from_pool(struct mempool *pool, void **elems,
 	 */
 	for (i = 0; i < count; i++)
 		kmemleak_update_trace(elems[i]);
-	return allocated;
+	return true;
 
 fail:
 	if (gfp_mask & __GFP_DIRECT_RECLAIM) {
@@ -454,7 +454,7 @@ static unsigned int mempool_alloc_from_pool(struct mempool *pool, void **elems,
 		spin_unlock_irqrestore(&pool->lock, flags);
 	}
 
-	return allocated;
+	return false;
 }
 
 /*
@@ -519,8 +519,8 @@ int mempool_alloc_bulk_noprof(struct mempool *pool, void **elems,
 	return 0;
 
 use_pool:
-	allocated = mempool_alloc_from_pool(pool, elems, count, allocated,
-			gfp_temp);
+	if (mempool_alloc_from_pool(pool, elems, count, allocated, gfp_temp))
+		return 0;
 	gfp_temp = gfp_mask;
 	goto repeat_alloc;
 }
-- 
2.55.0


  reply	other threads:[~2026-08-06 22:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-06 22:10 [PATCH 0/3] Fix a deadlock in blk-crypto-fallback Eric Biggers
2026-08-06 22:10 ` Eric Biggers [this message]
2026-08-06 22:10 ` [PATCH 2/3] mm: support fallible mempool_alloc_bulk() Eric Biggers
2026-08-06 22:10 ` [PATCH 3/3] blk-crypto-fallback: Fix deadlock when encrypting large bio in dm layer Eric Biggers

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