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Mon, 30 Mar 2026 02:58:56 -0700 (PDT) Received: from redhat.com ([209.132.188.88]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35d908216ddsm3613964a91.5.2026.03.30.02.58.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2026 02:58:56 -0700 (PDT) Date: Mon, 30 Mar 2026 17:58:53 +0800 From: Li Wang To: akpm@linux-foundation.org, rppt@kernel.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org Cc: aubaker@redhat.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v3] selftests/mm: skip hugetlb_dio tests when DIO alignment is incompatible Message-ID: References: <20260330053915.75442-1-liwang@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260330053915.75442-1-liwang@redhat.com> Reply to Sashiko: > + if (start_off % dio_align != 0 || writesize % dio_align != 0) { > + ksft_test_result_skip("DIO alignment (%u) incompatible with " > + "buf offset %u and writesize %zu\n", > + dio_align, start_off, writesize); > + return; > + } > Does start_off represent the memory buffer alignment rather than the file > offset alignment? > If it represents the memory buffer offset within the page-aligned hugepage, > should it be validated against stx_dio_mem_align instead of > stx_dio_offset_align? Hmm, I don't believe this unless you give me strong evidence here! After looking though Filesystems for handling the direct IO process, I just found that Btrfs does the buffer-address alignment check but it uses the dio_offset_align rather than dio_mem_align. And, the check_direct_IO() does not actually distinguish between the two alignments in its fast-path check. It applies dio_offset_align uniformly to pos, length, and buffer address. Also, I tried the reproducer on Btrfs, ext2/3/4, xfs, vfat, ntfs, all get passed with this patch. So I'd keep the patch not check for dio_mem_align. -- Regards, Li Wang