From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sphereful.davidgow.net (sphereful.davidgow.net [203.29.242.92]) (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 5B02B46AECF for ; Fri, 21 Aug 2026 09:19:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.29.242.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787303986; cv=none; b=AC/UtNSxZnJn2wpAVf/ry02SNwPXhhncdHzWjQixK9OjqNC+345I8Xp/a08lXhXFznhu+uZ1+vSEiw8xa2h8QTwvuTXB6v/qMEl4GSWzIBer+9p7venADQ+NBL6OxCghjkNj0C8e+8ylg1JbNf7ClKj00txg0R/NYsS2QLnTaso= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787303986; c=relaxed/simple; bh=0rjC25agwgZnATmSkdMF/oyJosyF2EPqlepmr8upOyw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fSamZe7ZywRf2w4KTMZxiI/afOVg0M25rYOc2h1/l02Nl+yRSJlgTCax7r8SKDNDuCmWrXWr//miJzFHBc0j2WzC62kfcvZDoxq6iRxiWujGgMJnG9wmezvOn0MT2UyoQknAXhaWvRF73C8A+wSvpBh/b6HTWFBhzxViTjGzYW0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ingeniumdigital.com; spf=fail smtp.mailfrom=ingeniumdigital.com; arc=none smtp.client-ip=203.29.242.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ingeniumdigital.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=ingeniumdigital.com Received: by sphereful.davidgow.net (Postfix, from userid 119) id B51CD1EAA61; Fri, 21 Aug 2026 17:19:34 +0800 (AWST) X-Spam-Level: Received: from shelley.lan (unknown [IPv6:2001:8003:8802:7000::41b]) by sphereful.davidgow.net (Postfix) with ESMTPSA id 772631EAA4D; Fri, 21 Aug 2026 17:19:29 +0800 (AWST) From: David Gow To: Jim Cromie , "Maciej W . Rozycki" , Andrew Morton , Matthew Auld , Arun Pravin , Joel Fernandes , David Airlie , Simona Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, David Gow Subject: [PATCH 2/2] drm_buddy: fix power-of-2 rounding errs Date: Fri, 21 Aug 2026 17:19:15 +0800 Message-ID: <20260821091918.1902032-2-david@ingeniumdigital.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260821091918.1902032-1-david@ingeniumdigital.com> References: <20260821091918.1902032-1-david@ingeniumdigital.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jim Cromie The standard roundup_pow_of_two() and rounddown_pow_of_two() macros use unsigned long internally, which on 32-bit architectures (like arm32) is a 32-bit type. drm_test_buddy_alloc_exceeds_max_order() uses these on a u64 value, where they silently truncate the 10GB allocation, giving unexpected success in DRM-CI. (see below the snip). Fix this by replacing the those macros with the safe 64-bit power-of-two equivalents added in the previous patch. Signed-off-by: Jim Cromie Signed-off-by: David Gow --- This should actually be version 13, I think, as it's just a rebase of v12 here, where it was part of a large series of fixups: https://lore.kernel.org/all/20260326185413.1205870-40-jim.cromie@gmail.com/ The major changes since that version are: - Add the helper functions rounddown_pow_of_two64() and roundup_pow_of_two64() (see patch 1) instead of open-coding them - Rebase now that the buddy allocator lives in drivers/gpu/buddy.c instead of drivers/gpu/drm/drm_buddy.c This is still breaking the gpu_test_buddy_alloc_exceeds_max_order KUnit test on 32-bit systems: [09:01:26] # gpu_test_buddy_alloc_exceeds_max_order: EXPECTATION FAILED at drivers/gpu/tests/gpu_buddy_test.c:1429 [09:01:26] Expected err == -22, but [09:01:26] err == 0 (0x0) [09:01:26] WARNING: drivers/gpu/buddy.c:508 at gpu_buddy_fini+0x244/0x2e0, CPU#0: kunit_try_catch/1595 [09:01:26] # gpu_test_buddy_alloc_exceeds_max_order: drivers/gpu/buddy.c:508: gpu_buddy_assert(gpu_buddy_block_is_free(mm->roots[i])) [09:01:26] WARNING: drivers/gpu/buddy.c:516 at gpu_buddy_fini+0x284/0x2e0, CPU#0: kunit_try_catch/1595 [09:01:26] # gpu_test_buddy_alloc_exceeds_max_order: drivers/gpu/buddy.c:508: gpu_buddy_assert(gpu_buddy_block_is_free(mm->roots[i])) [09:01:26] WARNING: drivers/gpu/buddy.c:516 at gpu_buddy_fini+0x284/0x2e0, CPU#0: kunit_try_catch/1595 [09:01:26] # gpu_test_buddy_alloc_exceeds_max_order: drivers/gpu/buddy.c:519: gpu_buddy_assert(!mm->used_scoreboard[i]) [09:01:26] [FAILED] gpu_test_buddy_alloc_exceeds_max_order Cheers, -- David --- drivers/gpu/buddy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c index a5553fcec28c..64f41f1fe908 100644 --- a/drivers/gpu/buddy.c +++ b/drivers/gpu/buddy.c @@ -1193,7 +1193,7 @@ static int __alloc_contig_try_harder(struct gpu_buddy *mm, u64 modify_size; int err; - modify_size = rounddown_pow_of_two(size); + modify_size = rounddown_pow_of_two64(size); order = ilog2(modify_size) - ilog2(mm->chunk_size); if (order == 0) return -ENOSPC; @@ -1440,7 +1440,7 @@ int gpu_buddy_alloc_blocks(struct gpu_buddy *mm, /* Roundup the size to power of 2 */ if (flags & GPU_BUDDY_CONTIGUOUS_ALLOCATION) { - size = roundup_pow_of_two(size); + size = roundup_pow_of_two64(size); min_block_size = size; /* * Normalize the requested size to min_block_size for regular allocations. -- 2.55.0