From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 179831DC985 for ; Tue, 24 Mar 2026 09:01:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774342864; cv=none; b=R+QFOTC7eQDv5lh9F6z8d7i7vObO714YB5MHakRrpC3P6wgGzpbPGDuuP6TYH6p3Ii2Q0AZk2L0LSds3OK2uOW5HU12Rqz6eJxQ6RtknS+23W9gWD9Mf4HJAPV8XB3XfhagWK7xHqFtZqO5AjcvYX6j2yTo7gW0cWUn5bxQilHE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774342864; c=relaxed/simple; bh=NUCt9499jjNNkuEEykHY4WzmSJ+p9GFYgLXZ1YnXaWc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=BQd9wkcgCPGDIdN3qw0nMi1+UhsQE/KIRVyobdhw2T9W8udOJdeat3siNkjO6IhlYmDFPPHUbEEKxruhVMPvXiwpgLm+QMjx6JZywcCOwVxLgiIZ+uLhK0ysAjzJRBNhul5QO55Tglf27TRm2pvx/LllJSrIyBjStu7aKLzo0Gc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=J083fDTN; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="J083fDTN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774342861; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=GAFdc90vtERiRN159wE1VgpqPHexiDdaSJGXbwhit1k=; b=J083fDTNNC9LxmjWwo5lySawsKA0/IDf4XQ2WMhrwH2wTO0eArOXQ7xmlC+c9jUhfIiC1m AJwB/nCrkGF4uzTGmiWnaj+LZzq/UB7Ic4TESH3IbFqiAfOhLRZ7r9tkI27BVPbH7tPe0S 1hfxKmPewvYnv7x9sAS2WNWFBedp0GM= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-2-RxjzfJo3NYqPteGTj33nqQ-1; Tue, 24 Mar 2026 05:00:59 -0400 X-MC-Unique: RxjzfJo3NYqPteGTj33nqQ-1 X-Mimecast-MFC-AGG-ID: RxjzfJo3NYqPteGTj33nqQ_1774342858 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6917A18002DC; Tue, 24 Mar 2026 09:00:58 +0000 (UTC) Received: from localhost (unknown [10.72.116.133]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 38A18180035F; Tue, 24 Mar 2026 09:00:56 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: Ming Lei , Yi Zhang Subject: [PATCH] bio: fix kmemleak false positives from percpu bio alloc cache Date: Tue, 24 Mar 2026 17:00:52 +0800 Message-ID: <20260324090052.1782766-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 When a bio is allocated from the mempool with REQ_ALLOC_CACHE set and later completed, bio_put() places it into the per-cpu bio_alloc_cache via bio_put_percpu_cache() instead of freeing it back to the mempool/slab. The slab allocation remains tracked by kmemleak, but the only reference to the bio is through the percpu cache's free_list, which kmemleak fails to trace through percpu memory. This causes kmemleak to report the cached bios as unreferenced objects. Use symmetric kmemleak_free()/kmemleak_alloc() calls to properly track bios across percpu cache transitions: - bio_put_percpu_cache: call kmemleak_free() when a bio enters the cache, unregistering it from kmemleak tracking. - bio_alloc_percpu_cache: call kmemleak_alloc() when a bio is taken from the cache for reuse, re-registering it so that genuine leaks of reused bios remain detectable. - __bio_alloc_cache_prune: call kmemleak_alloc() before bio_free() so that kmem_cache_free()'s internal kmemleak_free() has a matching allocation to pair with. Cc: Yi Zhang Signed-off-by: Ming Lei --- block/bio.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/block/bio.c b/block/bio.c index d80d5d26804e..093006e5aba0 100644 --- a/block/bio.c +++ b/block/bio.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include "blk.h" @@ -504,6 +505,9 @@ static struct bio *bio_alloc_percpu_cache(struct block_device *bdev, cache->nr--; put_cpu(); + kmemleak_alloc((void *)bio - bs->front_pad, + kmem_cache_size(bs->bio_slab), 1, gfp); + if (nr_vecs) bio_init_inline(bio, bdev, nr_vecs, opf); else @@ -765,6 +769,9 @@ static int __bio_alloc_cache_prune(struct bio_alloc_cache *cache, while ((bio = cache->free_list) != NULL) { cache->free_list = bio->bi_next; cache->nr--; + kmemleak_alloc((void *)bio - bio->bi_pool->front_pad, + kmem_cache_size(bio->bi_pool->bio_slab), + 1, GFP_KERNEL); bio_free(bio); if (++i == nr) break; @@ -828,6 +835,7 @@ static inline void bio_put_percpu_cache(struct bio *bio) bio->bi_bdev = NULL; cache->free_list = bio; cache->nr++; + kmemleak_free((void *)bio - bio->bi_pool->front_pad); } else if (in_hardirq()) { lockdep_assert_irqs_disabled(); @@ -835,6 +843,7 @@ static inline void bio_put_percpu_cache(struct bio *bio) bio->bi_next = cache->free_list_irq; cache->free_list_irq = bio; cache->nr_irq++; + kmemleak_free((void *)bio - bio->bi_pool->front_pad); } else { goto out_free; } -- 2.53.0