From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 31079231830; Sun, 21 Dec 2025 09:49:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766310563; cv=none; b=r9d4Dess6nS5vXXWNAzd+sidVDSFuFF+lsOyRQORKnrWTzkF9sAtEUcMfn0UgneCekvS1dUNHtsn+D6WS/Ni7h1wtUKb5QCh03R03YowzAvPNZGqY2niGnCN7b1wDYB4dCdB34RBvXW47w5RZ5BgRB3zb18KWljaKHVAE52eT24= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766310563; c=relaxed/simple; bh=tsj0Y9TsuBsyw04bXuGsZP/6xPjK8Tcxqhyw9abf304=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=F8RPn9+ASX0TXCnlOOLG/i0bHLt8WAXVYUlFNoA0caFOpbqTG+t8aPRrK82vyDWbkQmo+Yej5qbzndgSY5jQaP1JwjrkPrLG2nL/72dhlDthePOissBvFqzB9D6ODnFZRDu6QCXnD/LnhneMGcVlgoWYjKU36smtqQSlx3dW9i0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=V04umGEW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="V04umGEW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9AFDC4CEFB; Sun, 21 Dec 2025 09:49:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766310562; bh=tsj0Y9TsuBsyw04bXuGsZP/6xPjK8Tcxqhyw9abf304=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=V04umGEWs1079s0RySfXElGgYq7u0L01Piv/Ll9FUuBkNTe7ru14oQDeU5DCCIUPo f+x4HOb2YQMqzKHd8oFMA/sW/C88DbVa50alSOhF7TvRWcHFG7k5TGGhHfGe2uRe2p R1ifo+skhV+wl3EMmFfKkp1i01b+NQM0gxZxHdUYIlfEUTZhUuqzLi+rcnjt+IIIwl 2/Ka5ruUdGsy/oiCbSQsTnMA8Pryp1Ek6Qi/WtzXg4ZqK8tt5uDemihfKlccNt4Vmy HNj+Jy1tF1VQFWxd5H9bxyrLfrkUGgJQh3edbHXAUe38uJ4A91K4V4ekbcHSofJGms 5EggwqIO6gS7w== Message-ID: <30a75bb5-7edd-42b1-9a94-8ffe017bdb0b@kernel.org> Date: Sun, 21 Dec 2025 10:49:18 +0100 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] selftests/mm/charge_reserved_hugetlb: fix hugetlbfs mount size for large hugepages To: Li Wang Cc: akpm@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mark Brown , Shuah Khan , Waiman Long References: <20251221085810.3163919-1-liwang@redhat.com> <20251221085810.3163919-4-liwang@redhat.com> <970fa015-9ec8-4903-8e2f-f3e847d550d1@kernel.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/21/25 10:44, Li Wang wrote: > David Hildenbrand (Red Hat) wrote: >> On 12/21/25 09:58, Li Wang wrote: >>> charge_reserved_hugetlb.sh mounts a hugetlbfs instance at /mnt/huge with >>> a fixed size of 256M. On systems with large base hugepages (e.g. 512MB), >>> this is smaller than a single hugepage, so the hugetlbfs mount ends up >>> with effectively zero capacity (often visible as size=0 in mount output). >>> >>> As a result, write_to_hugetlbfs fails with ENOMEM and the test can hang >>> waiting for progress. >> >> I'm curious, what's the history of using "256MB" in the first place (or >> specifying any size?). > > Seems the script initializes it with "256MB" from: > > commit 29750f71a9b4cfae57cdddfbd8ca287eddca5503 > Author: Mina Almasry > Date: Wed Apr 1 21:11:38 2020 -0700 > > hugetlb_cgroup: add hugetlb_cgroup reservation tests What would happen if we don't specify a size at all? -- Cheers David