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 697531A0728; Sun, 3 May 2026 08:48:43 +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=1777798123; cv=none; b=h15W4SC3eRuAUoZ26Sj4/jD+/9dlpOaeVKG+KjsHpLadz+4WC07iEUqZzerAwm8321WR13IGgaV3HjJlTsHUFppnN7jjBs3y7IOoKzExUSXN66rCq4C122jXxMBGq2F8tRXKRkM/5W8TraJPYcA734RYW+ydPR+m85LqFiSCT5M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777798123; c=relaxed/simple; bh=Wbux98YSlt9p4yMEYN/6OibBDq2tLkjqLsbaIfyloMI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QYDmqol427+nqlg2Mf9husQ3izUDKrJveaF/0IrKe5MYDq9rF7KBrx32+TvcTRF3+7EJG624Um/5x1+HRijeWjl8PgYSn8HDghcj2J0MS0hszdAMlQz4aUVoVkSbSE6MzUchExrU44tFhwjvL3kZ3M9YVUtRrN1jlqWsULvFUNY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ImGibRl4; 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="ImGibRl4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53FA9C2BCB4; Sun, 3 May 2026 08:48:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777798123; bh=Wbux98YSlt9p4yMEYN/6OibBDq2tLkjqLsbaIfyloMI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ImGibRl4GZlBpEsgk89z5akvxGngy7i/7SEdecQsQ4Y3z2LkRW68bkdabl77lARru 6Bwm4bS3xqNdn/tDbw7O74JBIrsqWEM8lL39w040M6BtrN94FBhJkBYsWAmrAmouUx YgPVuWE1RkPtPKVwJLkuOb+DYld/b7zxZe/Pnv8/lgBGcWNkchILygEPxbhtkC7Y8/ eViGATJVpH+o0/zdnO37KjpjmRH5VdRXsdVpavB6qpB687SbmJYdJLnmZIqlvJu/Gz nhT/eoEOkslbrsWb2Zh8muryP/dI0LGx7Tm4mx+bmpYD1dZJRZCmml/KGeqjoJAxzY 3eBXcY4sGjRqw== Date: Sun, 3 May 2026 10:48:36 +0200 From: Mike Rapoport To: Vineet Agarwal Cc: shuah@kernel.org, akpm@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, surenb@google.com, mhocko@suse.com Subject: Re: [PATCH v2] selftests/mm: ksm-functional-tests: fix partial write handling Message-ID: References: <20260502005702.593878-1-agarwal.vineet2006@gmail.com> <20260503060234.644650-1-agarwal.vineet2006@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260503060234.644650-1-agarwal.vineet2006@gmail.com> On Sun, May 03, 2026 at 11:30:30AM +0530, Vineet Agarwal wrote: > Update write() checks to properly detect and handle partial writes. > > Previously, partial writes (ret > 0 && ret != len) would return > -errno, but write() does not set errno in this case. This could > result in returning 0 and incorrectly signaling success. > > Fix this by: > - returning -errno only on actual failures (ret < 0) > - returning -EIO when a partial write is detected > > This ensures partial writes are treated as errors and prevents > false success reporting in tests. > > Signed-off-by: Vineet Agarwal > > Changes in v2: > - Fix incorrect use of -errno on partial writes > - Return -EIO when write() completes partially Please start a new thread for a new version of the patch. > --- > tools/testing/selftests/mm/ksm_functional_tests.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c > index 9a8c852acd68..c80254cda926 100644 > --- a/tools/testing/selftests/mm/ksm_functional_tests.c > +++ b/tools/testing/selftests/mm/ksm_functional_tests.c > @@ -507,9 +507,13 @@ static int start_ksmd_and_set_frequency(char *pages_to_scan, char *sleep_ms) > if (write(ksm_fd, "1", 1) != 1) > return -errno; > > - ret = write(pages_to_scan_fd, pages_to_scan, strlen(pages_to_scan)); > - if (ret < 0 || ret != strlen(pages_to_scan)) > + ssize_t len = strlen(pages_to_scan); The v2 diff should be against the base, not against v1. > + > + ret = write(pages_to_scan_fd, pages_to_scan, len); > + if (ret < 0) > return -errno; > + if (ret != len) > + return -EIO; Just return -1 if write() != strlen(), the actual error code does not matter anyway. > ret = write(sleep_millisecs_fd, sleep_ms, strlen(sleep_ms)); > if (ret < 0 || ret != strlen(sleep_ms)) > @@ -531,8 +535,10 @@ static int stop_ksmd_and_restore_frequency(void) > return -errno; > > ret = write(pages_to_scan_fd, "100", 3); > - if (ret < 0 || ret != 3) > + if (ret < 0) > return -errno; > + if (ret != 3) > + return -EIO; > > ret = write(sleep_millisecs_fd, "20", 2); > if (ret < 0 || ret != 2) > -- > 2.54.0 > -- Sincerely yours, Mike.