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Tue, 26 Aug 2025 12:49:28 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4FCFB20043; Tue, 26 Aug 2025 12:49:28 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DFAB120040; Tue, 26 Aug 2025 12:49:25 +0000 (GMT) Received: from li-218185cc-29b5-11b2-a85c-9a1300ae2e6e.in.ibm.com (unknown [9.109.215.183]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 26 Aug 2025 12:49:25 +0000 (GMT) From: Donet Tom To: Andrew Morton , David Hildenbrand Cc: Ritesh Harjani , Xu Xin , Chengming Zhou , Wei Yang , Aboorva Devarajan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Donet Tom Subject: [PATCH 1/2] mm/ksm: Reset KSM counters in mm_struct during fork Date: Tue, 26 Aug 2025 18:19:21 +0530 Message-ID: <2e662107e01417bf9af23bc7f52863cd538419be.1756211338.git.donettom@linux.ibm.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIzMDAxMCBTYWx0ZWRfXydYkEKYVYR12 9GYbng7zDTwaFmkIyJ+1SHjYxLupFkAQYTBOEytf0HF6SthYXCjLx1K7UOCkvFV+DQoaY4OgRdU EuADlD7T5u+W2Ng4cjr5/9qeLp23k/obauCT2cqGeAtSEhrdXGWmd5Y12LXPlhNUgC8M123f5Rw J/kdDw3n13wzPJnEG3gedGUe6JnAVVPyEus94r6R8tIgC2na9VGv3HS4Z3pzgjAWAJ/INvKyMZr /H7J1NmTn1uZXdM5HqYKA1IWIhZdZk+M2KjdhUf8lS3sKHiGwYdEAwJtZoFkkTQTdSCqfCutp4C ctEV9OIs5W6bUX/7o0t1eg9iPOmXB+gsjP9aSOdKbJ7T+ZZw+FkCHYXs5uYgjtCtWPmZzxR33m9 vYPo1Qrn X-Proofpoint-ORIG-GUID: X1kt7dpWXr41pu_7Z6YhmU7QhZ9kIS_o X-Proofpoint-GUID: Dz170ztLRn2G-QQbmUmmLpUe42C34bRS X-Authority-Analysis: v=2.4 cv=evffzppX c=1 sm=1 tr=0 ts=68adad5d cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=2OwXVqhp2XgA:10 a=VnNF1IyMAAAA:8 a=bffXwCTgIVeg__Yz0z8A:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-26_02,2025-08-26_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 malwarescore=0 spamscore=0 bulkscore=0 impostorscore=0 clxscore=1011 priorityscore=1501 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508230010 Currently, the KSM-related counters in `mm_struct` such as `ksm_merging_pages`, `ksm_rmap_items`, and `ksm_zero_pages` are inherited by the child process during fork. This results in incorrect accounting, since the child has not performed any KSM page merging. To fix this, reset these counters to 0 in the newly created `mm_struct` during fork. This ensures that KSM statistics remain accurate and only reflect the activity of each process. Signed-off-by: Donet Tom --- include/linux/ksm.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 22e67ca7cba3..61b8892c632b 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -56,8 +56,12 @@ static inline long mm_ksm_zero_pages(struct mm_struct *mm) static inline void ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) { /* Adding mm to ksm is best effort on fork. */ - if (mm_flags_test(MMF_VM_MERGEABLE, oldmm)) + if (mm_flags_test(MMF_VM_MERGEABLE, oldmm)) { + mm->ksm_merging_pages = 0; + mm->ksm_rmap_items = 0; + atomic_long_set(&mm->ksm_zero_pages, 0); __ksm_enter(mm); + } } static inline int ksm_execve(struct mm_struct *mm) -- 2.51.0