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Fri, 14 Aug 2026 11:30:09 +0000 (GMT) Received: from localhost (unknown [9.111.42.87]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTPS; Fri, 14 Aug 2026 11:30:09 +0000 (GMT) Date: Fri, 14 Aug 2026 13:30:08 +0200 From: Vasily Gorbik To: Heiko Carstens Cc: Christoph Schlameuss , Alexander Egorenkov , Alexander Gordeev , Sven Schnelle , Christian Borntraeger , linux-s390@vger.kernel.org Subject: Re: [PATCH] s390/time: Use jiffies instead of jiffies_64 Message-ID: References: <20260813132505.3691502-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260813132505.3691502-1-hca@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=RsP16imK c=1 sm=1 tr=0 ts=6a7efc46 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=IbkYLJS4NRrwR7yNVBcA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: acsZ5bVXn6LHOi78T2wCRD4Ye2cmX9k7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE0MDA4MyBTYWx0ZWRfXxmiBT5DwJ9ZE eti7IV1c++Kj89x7fdhN4f8T0Z35VqXCm4i+vSmLyA08b7r9INk8JUsP2opShBISZVx0p3WW5GG 3lK05Tx84ik06/E1uk8y3Rw+7mkZH3KSeamFsTt0PF+yObeWrhp6RSaluC1Igp/w0SrdVWJoMbf /4Kcbk4N0jIm3jcZv9C3a2m6Ba7rozy+xsMM29nEF3WoXLkSjuN3V6WLnX/UpSXCt8OyzIbLUuj DwUluMjpncJBoPjKEfy/19EwYU5vfEDsNVXaMqWvy7Ly9KMrB8JRVR/b13MPZ4lyjVayOrOQ4sb oBVRrMhQEEdIQBPPASK24NGNQG7SUr0ONMSL7SQuzgAMZbLu5W6/uj97Y/Y/vU0p0ojL0oaVjit YO3FEkTymOYZoASBdjkNI/QkmF0nCVp+SmuGumYP03BryeSfVafE+ksxL30mzly4ZTPV+ZNkDlV MEIMej5repaz4jWp2Ag== X-Proofpoint-ORIG-GUID: acsZ5bVXn6LHOi78T2wCRD4Ye2cmX9k7 X-Proofpoint-Spam-Info: AW1haW4tMjYwODE0MDA4MyBTYWx0ZWRfX12etDv4MQhLy NnoAOj3YoWgRMgV0G4RJ7CEcgw642oeYJKgxguvuBOsn4eTusW9OrZaA0pY2PhTJ4/AbTE9zcqd FT/7QSoik0aPuuyDKiWLyGsO9A4i9ic= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-14_04,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1015 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608140083 On Thu, Aug 13, 2026 at 03:25:05PM +0200, Heiko Carstens wrote: > Christoph Schlameuss and Alexander Egorenkov reported a data-race > reported by KCSAN when jiffies_64 is read: > > ================================================================== > BUG: KCSAN: data-race in do_account_vtime / tick_do_update_jiffies64 > > write to 0x0000016599ea8600 of 8 bytes by interrupt on cpu 6: > tick_do_update_jiffies64+0x140/0x250 > =============================================================> > BUG: KCSAN: data-race in do_account_vtime / tick_do_update_ji> > > write to 0x0000016599ea8600 of 8 bytes by interrupt on cpu 6: > tick_do_update_jiffies64+0x140/0x250 > tick_nohz_handler+0x2e6/0x300 > __run_hrtimer+0x156/0x4d0 > __hrtimer_run_queues+0xd2/0x150 > ... > system_call+0x72/0x90 > > read to 0x0000016599ea8600 of 8 bytes by interrupt on cpu 12: > do_account_vtime+0x7d6/0x860 > vtime_flush+0x26/0xe0 > update_process_times+0x32/0x160 > tick_nohz_handler+0x12a/0x300 > ... > system_call+0x72/0x90 > > value changed: 0x00000000ffffaa6c -> 0x00000000ffffaa6d > ... > =============================================================> > > Problem is that jiffies_64 instead of jiffies is used. Both are at the > same address, but only jiffies is of volatile type, which prevents this > warning. > > Change the vtime code so jiffies instead of jiffies_64 is used > everywhere. This addresses also the inconsistency that both jiffies and > jiffies_64 were used in the original patch which introduced this. > > Fixes: f341b8dff982 ("s390/vtime: limit MT scaling value updates") > Reported-by: Christoph Schlameuss > Reported-by: Alexander Egorenkov > Signed-off-by: Heiko Carstens > --- > arch/s390/kernel/vtime.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) Applied, thank you!