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 B3F5C156F30; Thu, 24 Oct 2024 03:00:02 +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=1729738803; cv=none; b=HBCWRg7PdI166aDDtDogAOh8vqjcQfk4ni54ZqNTtINbyqx7L14udZaQc3Ofhi8zbtSxIj+1tOOrTLWSsIDyMpCPhyytK1fSlRdgb4HpDX+AxgKTm+8DG0f7lcaEaW6oT5RFyWRrOqje7wAgw+1VZVTsXlFEAEIRhTGK4qGY15U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729738803; c=relaxed/simple; bh=Y4iOGP+DCwBj9Plp01TpcArgJAABKF2G0i6KPJefUz4=; h=Date:To:From:Subject:Message-Id; b=AlyJMieARm13l2ax4Phf3SbhfVX2fmavV4ThWYYa5BVMlbKeJa++S8PaMRlcWaz2yGDYiH1h5+fz1UKXzCAgW7+lxKHUf6rxefyN68PvzqkB2ykT+0xR9FxQbnHH/qtAdtmHXg+isUmYLsKozsr9daD37Z8DpDIFePndmd4u3+c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=m7EKQeeU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="m7EKQeeU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AA7BC4CEC6; Thu, 24 Oct 2024 03:00:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1729738802; bh=Y4iOGP+DCwBj9Plp01TpcArgJAABKF2G0i6KPJefUz4=; h=Date:To:From:Subject:From; b=m7EKQeeUWBZ/z1tQ2ojkpkCr+yuKMVvwv+2IetD6E8LrttQzoh24AOPYRS8s2eUV4 3U+FUbpaayxyQm94OTelHRAtUPF6JDtvQUA+bP700uPFTdgjBqaW+cJVeaUVPyaFT1 5HNLyTxcj0eWVOAR/szP2gJRFChAvEmTkEhMPGpU= Date: Wed, 23 Oct 2024 20:00:01 -0700 To: mm-commits@vger.kernel.org,yeweihua4@huawei.com,stable@vger.kernel.org,sj@kernel.org,sieberf@amazon.com,shakeel.butt@linux.dev,foersleo@amazon.de,zhengyejian@huaweicloud.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-damon-vaddr-fix-issue-in-damon_va_evenly_split_region.patch added to mm-unstable branch Message-Id: <20241024030002.1AA7BC4CEC6@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/damon/vaddr: fix issue in damon_va_evenly_split_region() has been added to the -mm mm-unstable branch. Its filename is mm-damon-vaddr-fix-issue-in-damon_va_evenly_split_region.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-vaddr-fix-issue-in-damon_va_evenly_split_region.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Zheng Yejian Subject: mm/damon/vaddr: fix issue in damon_va_evenly_split_region() Date: Tue, 22 Oct 2024 16:39:26 +0800 Patch series "mm/damon/vaddr: Fix issue in damon_va_evenly_split_region()". v2. According to the logic of damon_va_evenly_split_region(), currently following split case would not meet the expectation: Suppose DAMON_MIN_REGION=0x1000, Case: Split [0x0, 0x3000) into 2 pieces, then the result would be acutually 3 regions: [0x0, 0x1000), [0x1000, 0x2000), [0x2000, 0x3000) but NOT the expected 2 regions: [0x0, 0x1000), [0x1000, 0x3000) !!! The root cause is that when calculating size of each split piece in damon_va_evenly_split_region(): `sz_piece = ALIGN_DOWN(sz_orig / nr_pieces, DAMON_MIN_REGION);` both the dividing and the ALIGN_DOWN may cause loss of precision, then each time split one piece of size 'sz_piece' from origin 'start' to 'end' would cause more pieces are split out than expected!!! To fix it, count for each piece split and make sure no more than 'nr_pieces'. In addition, add above case into damon_test_split_evenly(). And add 'nr_piece == 1' check in damon_va_evenly_split_region() for better code readability and add a corresponding kunit testcase. This patch (of 2): According to the logic of damon_va_evenly_split_region(), currently following split case would not meet the expectation: Suppose DAMON_MIN_REGION=0x1000, Case: Split [0x0, 0x3000) into 2 pieces, then the result would be acutually 3 regions: [0x0, 0x1000), [0x1000, 0x2000), [0x2000, 0x3000) but NOT the expected 2 regions: [0x0, 0x1000), [0x1000, 0x3000) !!! The root cause is that when calculating size of each split piece in damon_va_evenly_split_region(): `sz_piece = ALIGN_DOWN(sz_orig / nr_pieces, DAMON_MIN_REGION);` both the dividing and the ALIGN_DOWN may cause loss of precision, then each time split one piece of size 'sz_piece' from origin 'start' to 'end' would cause more pieces are split out than expected!!! To fix it, count for each piece split and make sure no more than 'nr_pieces'. In addition, add above case into damon_test_split_evenly(). After this patch, damon-operations test passed: # ./tools/testing/kunit/kunit.py run damon-operations [...] ============== damon-operations (6 subtests) =============== [PASSED] damon_test_three_regions_in_vmas [PASSED] damon_test_apply_three_regions1 [PASSED] damon_test_apply_three_regions2 [PASSED] damon_test_apply_three_regions3 [PASSED] damon_test_apply_three_regions4 [PASSED] damon_test_split_evenly ================ [PASSED] damon-operations ================= Link: https://lkml.kernel.org/r/20241022083927.3592237-1-zhengyejian@huaweicloud.com Link: https://lkml.kernel.org/r/20241022083927.3592237-2-zhengyejian@huaweicloud.com Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces") Signed-off-by: Zheng Yejian Reviewed-by: SeongJae Park Cc: Fernand Sieber Cc: Leonard Foerster Cc: Shakeel Butt Cc: Ye Weihua Cc: Signed-off-by: Andrew Morton --- mm/damon/tests/vaddr-kunit.h | 1 + mm/damon/vaddr.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) --- a/mm/damon/tests/vaddr-kunit.h~mm-damon-vaddr-fix-issue-in-damon_va_evenly_split_region +++ a/mm/damon/tests/vaddr-kunit.h @@ -300,6 +300,7 @@ static void damon_test_split_evenly(stru damon_test_split_evenly_fail(test, 0, 100, 0); damon_test_split_evenly_succ(test, 0, 100, 10); damon_test_split_evenly_succ(test, 5, 59, 5); + damon_test_split_evenly_succ(test, 0, 3, 2); damon_test_split_evenly_fail(test, 5, 6, 2); } --- a/mm/damon/vaddr.c~mm-damon-vaddr-fix-issue-in-damon_va_evenly_split_region +++ a/mm/damon/vaddr.c @@ -67,6 +67,7 @@ static int damon_va_evenly_split_region( unsigned long sz_orig, sz_piece, orig_end; struct damon_region *n = NULL, *next; unsigned long start; + unsigned int i; if (!r || !nr_pieces) return -EINVAL; @@ -80,8 +81,7 @@ static int damon_va_evenly_split_region( r->ar.end = r->ar.start + sz_piece; next = damon_next_region(r); - for (start = r->ar.end; start + sz_piece <= orig_end; - start += sz_piece) { + for (start = r->ar.end, i = 1; i < nr_pieces; start += sz_piece, i++) { n = damon_new_region(start, start + sz_piece); if (!n) return -ENOMEM; _ Patches currently in -mm which might be from zhengyejian@huaweicloud.com are mm-damon-vaddr-fix-issue-in-damon_va_evenly_split_region.patch mm-damon-vaddr-add-nr_piece-==-1-check-in-damon_va_evenly_split_region.patch