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Shutemov" , Joerg Roedel , Uros Bizjak , Alistair Popple , linux-arch References: <47678198-C502-47E1-B7C8-8A12352CDA95@gmail.com> <140B437E-B994-45B7-8DAC-E9B66885BEEF@gmail.com> <50458458-9b57-aa5a-0d67-692cc4dbf2ad@linux.ibm.com> In-Reply-To: <50458458-9b57-aa5a-0d67-692cc4dbf2ad@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: UDdyLz1E_Xsj1yAmifuKyKg5Pf6QSyRD X-Proofpoint-ORIG-GUID: ipXGWaYxPYvQaeM7wsv-w7TWwzyNWfg- Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-02_06,2022-11-01_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 phishscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 adultscore=0 mlxscore=0 spamscore=0 malwarescore=0 mlxlogscore=999 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211020051 ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=X8pjC1k9; spf=pass (imf18.hostedemail.com: domain of borntraeger@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=borntraeger@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667381025; a=rsa-sha256; cv=none; b=xE3mbEHarIjKiblAF14vZKQ8cPg7D4uO7OZLKHBGgM8cBgVs6feh49eFArLiyqzQ1iNliu Eu7Qx0rxa9zfFpNwlMm9o4cVtwErGLKXnnLlVDISaPyeaKPjNPeDIKDJaXYIAvWWutD0Rp m8uZYHmgExc/AAoNNzEursNSZnHjpxY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667381025; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=qKNG/iEjhfX4MSTdr2BXv+H5ooqOhmzMbIYzJ2wh8C0=; b=bSuRqN2gJesjtiOEPv28xYnpmTExYSXqLISPpAXvQBVeBt+rdxJWSYv4KN67zA7iun+DPQ 67pvU9rmhgpENGmTbjPfI6VTXkCJpFeTIzfk7+dcLbJkwLp5/OzeyKVBArrT8AeRgWLzTu cakGPAo4tBuTc9R6odZ73FDoT9ZLT80= X-Stat-Signature: kfwj9kjz1f67ddsnatbgnh4ktujkf1xn X-Rspamd-Queue-Id: A82A91C000A X-Rspam-User: Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=X8pjC1k9; spf=pass (imf18.hostedemail.com: domain of borntraeger@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=borntraeger@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com X-Rspamd-Server: rspam01 X-HE-Tag: 1667381025-41483 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Am 02.11.22 um 10:14 schrieb Christian Borntraeger: > Am 31.10.22 um 19:43 schrieb Linus Torvalds: >> Updated subject line, and here's the link to the original discussion >> for new people: >> >>      https://lore.kernel.org/all/B88D3073-440A-41C7-95F4-895D3F657EF2@gmail.com/ >> >> On Mon, Oct 31, 2022 at 10:28 AM Linus Torvalds >> wrote: >>> >>> Ok. At that point we no longer have the pte or the virtual address, so >>> it's not going to be exactly the same debug output. >>> >>> But I think it ends up being fairly natural to do >>> >>>          VM_WARN_ON_ONCE_PAGE(page_mapcount(page) < 0, page); >>> >>> instead, and I've fixed that last patch up to do that. >> >> Ok, so I've got a fixed set of patches based on the feedback from >> PeterZ, and also tried to do the s390 updates for this blindly, and >> pushed them out into a git branch: >> >>      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?h=mmu_gather-race-fix >> >> If people really want to see the patches in email again, I can do >> that, but most of you already have, and the changes are either trivial >> fixes or the s390 updates. >> >> For the s390 people that I've now added to the participant list maybe >> the git tree is fine - and the fundamental explanation of the problem >> is in that top-most commit (with the three preceding commits being >> prep-work). Or that link to the thread about this all. > > Adding Gerald. now the correct Gerald.... > >> >> That top-most commit is also where I tried to fix things up for s390 >> that uses its own non-gathering TLB flush due to >> CONFIG_MMU_GATHER_NO_GATHER. >> >> NOTE NOTE NOTE! Unlike my regular git branch, this one may end up >> rebased etc for further comments and fixes. So don't consider that >> stable, it's still more of an RFC branch. >> >> At a minimum I'll update it with Ack's etc, assuming I get those, and >> my s390 changes are entirely untested and probably won't work. >> >> As far as I can tell, s390 doesn't actually *have* the problem that >> causes this change, because of its synchronous TLB flush, but it >> obviously needs to deal with the change of rmap zapping logic. >> >> Also added a few people who are explicitly listed as being mmu_gather >> maintainers. Maybe people saw the discussion on the linux-mm list, but >> let's make it explicit. >> >> Do people have any objections to this approach, or other suggestions? >> >> I do *not* consider this critical, so it's a "queue for 6.2" issue for me. >> >> It probably makes most sense to queue in the -MM tree (after the thing >> is acked and people agree), but I can keep that branch alive too and >> just deal with it all myself as well. >> >> Anybody? >> >>                       Linus > > It certainly needs a build fix for s390: > > > In file included from kernel/sched/core.c:78: > ./arch/s390/include/asm/tlb.h: In function '__tlb_remove_page_size': > ./arch/s390/include/asm/tlb.h:50:17: error: implicit declaration of function 'page_zap_pte_rmap' [-Werror=implicit-function-declaration] >    50 |                 page_zap_pte_rmap(page); >       |                 ^~~~~~~~~~~~~~~~~