From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 BB00214EC4C for ; Fri, 26 Apr 2024 16:12:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714147966; cv=none; b=OUhnGCVqaOJUs5+AkTuVkHFjJMV98RvLGQbxa4qXwcp6oby0y7NMRzhBtdbWRpxiE2j24QQ9xcYYphBcQFrjHEEby3vev6HSyMwAFAS4ILHJkYln04lk0swoL7D1ctyBzOGif062CF50pVr++p7sMv6I2ZHqR94PX4eamaIH+IU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714147966; c=relaxed/simple; bh=VHk3yV3ykPgBDTFB6jGO3B/kKnE4mwuV8+QA4otgjj8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uWVXiMBc5JcJd0JenkczOeKnjy6L9kshfqPeLMjFQukn6sEe3kz7EwfJFOndR9TiFNTPcBhlI6Yz+1/yz42Pmf+A6QNjl6jDOhfT+sPHGqBlmxaRDm49sN7ma1UL9cVbW3zsyS3K7oH/Fg72bpXHHzUtI6IIoILwqyIIZBwzF08= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=LypP9JvO; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LypP9JvO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714147963; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=LypP9JvOUwTJ+H67rwONo9wwRCDu7c4QosQU9i/xSC7EmmvETQP+nnNJgYw4vxqKKqI2rT p6+9SIKxj7B8VcSqnaf+5p3cIiRNM+TEH2OxbP52yBiEALFUWqq9N6PaG46XJ+JZ/4ZpKC y8QXaCCaiIVIz4CAWLMaud9ezd13PoQ= Received: from mail-ot1-f70.google.com (mail-ot1-f70.google.com [209.85.210.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-251-6IPr-_5oNPG5U0bClftkUg-1; Fri, 26 Apr 2024 12:12:42 -0400 X-MC-Unique: 6IPr-_5oNPG5U0bClftkUg-1 Received: by mail-ot1-f70.google.com with SMTP id 46e09a7af769-6eb607b308bso730680a34.0 for ; Fri, 26 Apr 2024 09:12:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714147961; x=1714752761; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=RSIAhAvXQv3fwd4JSUHXf2eC1/H/WIaeWW5nE7IuJj/D/KV5Qv3uX4JNb/g2ftGFWe CsvwXa7EsCvzRJWE26LYAQGFlYiOmGgadT4I8ksepAvokcS1nZ8XGCKZUl7B5WPmrO0T y7+TrdIq8ynIXRcCM50zU8mrDefzhlRlFBgr8U3AWLhpf2HkrYXLCe7ADdreoWyAM+fr EvM13u+S3rg6tBGkgoiDI6Cj3xzgCqudehPtbkeix2HzpX4NXw/G2kL88BBPR3vRLOGy Vl6EUdmWeAk8M1DDixJ8Jsw/FtrlS5fdAv6B52NjM+FiqQsxy1yMT4zeQ/COWaoxx/gu pfwg== X-Forwarded-Encrypted: i=1; AJvYcCX10a2U6EdUaEgpSb9HbS6Bc9AD0PnCBXnNp4U9Ufzyv4zw7qTE8Vn0zBhPT+5wnPu9Bb3yJusoFDC3Z5TqrgCP5iIDAX0e8tFADw== X-Gm-Message-State: AOJu0YxtttaEvzWKSkd3Z2jQQVxoRE3uSQKufHvvud+9Si8iGSTuo3nJ xL1UMRYbP9/laFfclKTlP/lA5UgwZdVx2SfBZZw3fuwSCXVj9pDjCixQJV3CKGMtui+XC3bR4/+ csAWNe7lYAydzICIjx/xjjnc3WxmCY6jLCRbfUmKhsOEBEY7hDj9R6enJDR0= X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125223oal.1.1714147961407; Fri, 26 Apr 2024 09:12:41 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFKK09FSsz1w18C9O+QSKywaneNtUpj/aPvoeb+SOH3u9egTJYXPSkxUgqSN3BOrRHAMYNm3w== X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125169oal.1.1714147960484; Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Received: from x1n (pool-99-254-121-117.cpe.net.cable.rogers.com. [99.254.121.117]) by smtp.gmail.com with ESMTPSA id m6-20020ac807c6000000b00434fd7d6d00sm8007149qth.2.2024.04.26.09.12.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Date: Fri, 26 Apr 2024 12:12:32 -0400 From: Peter Xu To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mike Rapoport , Jason Gunthorpe , John Hubbard , linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions Message-ID: References: <20240402125516.223131-1-david@redhat.com> <20240402125516.223131-2-david@redhat.com> Precedence: bulk X-Mailing-List: linux-mips@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: On Fri, Apr 26, 2024 at 09:44:58AM -0400, Peter Xu wrote: > On Fri, Apr 26, 2024 at 09:17:47AM +0200, David Hildenbrand wrote: > > On 02.04.24 14:55, David Hildenbrand wrote: > > > Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename > > > all relevant internal functions to start with "gup_fast", to make it > > > clearer that this is not ordinary GUP. The current mixture of > > > "lockless", "gup" and "gup_fast" is confusing. > > > > > > Further, avoid the term "huge" when talking about a "leaf" -- for > > > example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the > > > "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that > > > stays. > > > > > > What remains is the "external" interface: > > > * get_user_pages_fast_only() > > > * get_user_pages_fast() > > > * pin_user_pages_fast() > > > > > > The high-level internal functions for GUP-fast (+slow fallback) are now: > > > * internal_get_user_pages_fast() -> gup_fast_fallback() > > > * lockless_pages_from_mm() -> gup_fast() > > > > > > The basic GUP-fast walker functions: > > > * gup_pgd_range() -> gup_fast_pgd_range() > > > * gup_p4d_range() -> gup_fast_p4d_range() > > > * gup_pud_range() -> gup_fast_pud_range() > > > * gup_pmd_range() -> gup_fast_pmd_range() > > > * gup_pte_range() -> gup_fast_pte_range() > > > * gup_huge_pgd() -> gup_fast_pgd_leaf() > > > * gup_huge_pud() -> gup_fast_pud_leaf() > > > * gup_huge_pmd() -> gup_fast_pmd_leaf() > > > > > > The weird hugepd stuff: > > > * gup_huge_pd() -> gup_fast_hugepd() > > > * gup_hugepte() -> gup_fast_hugepte() > > > > I just realized that we end up calling these from follow_hugepd() as well. > > And something seems to be off, because gup_fast_hugepd() won't have the VMA > > even in the slow-GUP case to pass it to gup_must_unshare(). > > > > So these are GUP-fast functions and the terminology seem correct. But the > > usage from follow_hugepd() is questionable, > > > > commit a12083d721d703f985f4403d6b333cc449f838f6 > > Author: Peter Xu > > Date: Wed Mar 27 11:23:31 2024 -0400 > > > > mm/gup: handle hugepd for follow_page() > > > > > > states "With previous refactors on fast-gup gup_huge_pd(), most of the code > > can be leveraged", which doesn't look quite true just staring the the > > gup_must_unshare() call where we don't pass the VMA. Also, > > "unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense for > > slow GUP ... > > Yes it's not needed, just doesn't look worthwhile to put another helper on > top just for this. I mentioned this in the commit message here: > > There's something not needed for follow page, for example, gup_hugepte() > tries to detect pgtable entry change which will never happen with slow > gup (which has the pgtable lock held), but that's not a problem to check. > > > > > @Peter, any insights? > > However I think we should pass vma in for sure, I guess I overlooked that, > and it didn't expose in my tests too as I probably missed ./cow. > > I'll prepare a separate patch on top of this series and the gup-fast rename > patches (I saw this one just reached mm-stable), and I'll see whether I can > test it too if I can find a Power system fast enough. I'll probably drop > the "fast" in the hugepd function names too. Hmm, so when I enable 2M hugetlb I found ./cow is even failing on x86. # ./cow | grep -B1 "not ok" # [RUN] vmsplice() + unmap in child ... with hugetlb (2048 kB) not ok 161 No leak from parent into child -- # [RUN] vmsplice() + unmap in child with mprotect() optimization ... with hugetlb (2048 kB) not ok 215 No leak from parent into child -- # [RUN] vmsplice() before fork(), unmap in parent after fork() ... with hugetlb (2048 kB) not ok 269 No leak from child into parent -- # [RUN] vmsplice() + unmap in parent after fork() ... with hugetlb (2048 kB) not ok 323 No leak from child into parent And it looks like it was always failing.. perhaps since the start? We didn't do the same on hugetlb v.s. normal anon from that regard on the vmsplice() fix. I drafted a patch to allow refcount>1 detection as the same, then all tests pass for me, as below. David, I'd like to double check with you before I post anything: is that your intention to do so when working on the R/O pinning or not? Thanks, ========= >From 7300c249738dadda1457c755b597c1551dfe8dc6 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 26 Apr 2024 11:41:12 -0400 Subject: [PATCH] mm/hugetlb: Fix vmsplice case on memory leak once more Signed-off-by: Peter Xu --- mm/hugetlb.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 417fc5cdb6ee..1ca102013561 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5961,10 +5961,13 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, retry_avoidcopy: /* - * If no-one else is actually using this page, we're the exclusive - * owner and can reuse this page. + * If the page is marked exlusively owned (e.g. longterm pinned), + * we can reuse it. Otherwise if no-one else is using this page, + * we can savely set the exclusive bit and reuse it. */ - if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) { + if (folio_test_anon(old_folio) && + (PageAnonExclusive(&old_folio->page) || + folio_ref_count(old_folio) == 1)) { if (!PageAnonExclusive(&old_folio->page)) { folio_move_anon_rmap(old_folio, vma); SetPageAnonExclusive(&old_folio->page); -- 2.44.0 -- Peter Xu From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D0522C4345F for ; Fri, 26 Apr 2024 16:12:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jRKr5ywc5MnmJhSSgDl+d7G0A+MIlIFo/dmKiF+r8jw=; b=XPKnw68Cjb1LTR RUvxv2X6wxkLBdt9XLST8PAisuBpYsuZM1I1bPU0J1Kvq/70qOlOMzVwzkUgCankxlPuM0kAJ7Msw LkiTubRXQaMsr/UGY/zyLr+QPSldnpWKhZHiQfSuglU/7XDxUzUH1T1+MdEjyLBJmwu6zgfsQLQGJ 3bfUdWok1avfCwePY4aCD8F46kIbULl+Zgsd0q+I14uji1K/uXNFz3dgP9hfe5DlUj9m1ioKpeiMO xJNaSTdCUeC7l/HTppnzgGqiJY7feL4zA+cVPJdvqvXhRgyuwRChr4G9mCBRoA6kQcJgs2dmNc2Av jq8rvW10s3X5N4o1VvqA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0OBu-0000000DCgN-1nZG; Fri, 26 Apr 2024 16:12:50 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0OBp-0000000DCe7-1FzB for linux-riscv@lists.infradead.org; Fri, 26 Apr 2024 16:12:47 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714147963; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=LypP9JvOUwTJ+H67rwONo9wwRCDu7c4QosQU9i/xSC7EmmvETQP+nnNJgYw4vxqKKqI2rT p6+9SIKxj7B8VcSqnaf+5p3cIiRNM+TEH2OxbP52yBiEALFUWqq9N6PaG46XJ+JZ/4ZpKC y8QXaCCaiIVIz4CAWLMaud9ezd13PoQ= Received: from mail-ot1-f69.google.com (mail-ot1-f69.google.com [209.85.210.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-222-sFe7WWm0Pv2EEEmaWwxSkA-1; Fri, 26 Apr 2024 12:12:42 -0400 X-MC-Unique: sFe7WWm0Pv2EEEmaWwxSkA-1 Received: by mail-ot1-f69.google.com with SMTP id 46e09a7af769-6eba7dc8f1dso621416a34.2 for ; Fri, 26 Apr 2024 09:12:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714147962; x=1714752762; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=IilnwLuWU1QXJiynvtKLpLRFJ2+7xADcGYOWAr/pO+Nu4H9Y0UYJ/nKx6hxbYZBddW dqWFzgEi8RXg8HhvAasUlMKGJgB/5bIEIqXk6S5YZi18qgdHt20fb7BudDmUQIgJbgg0 4EI3Hr+pdwzLyTxSJA1hUk3yUCJ67/09ndxA8mwj9cMzJs5h+C8URWiM67+wcTQ0+zVl eMQYb4yOQv9+CrdW59Yse9H6dKQCbM3GWRjd3GEHmtGVJCdJILLvjK28TdSTzzLtNSdP K1AncelQWuUspUiwUaxWdudFck+Z+E9gFcYYgqmmeZkV0SSRZ+vzMbeLTLDp7xhSFbqK /+5Q== X-Forwarded-Encrypted: i=1; AJvYcCXNTeaQP51bOMHOpLpyV9dxssf3yvms5EdkcnRc3D6sWhuux11p/YZ7rjlESJM3Qm47pZIkvkqXzEtG0jIRZ9pT/VOoreAuzZqp6N058oAa X-Gm-Message-State: AOJu0YwbmAL0kvhD9HAsDdRDClSabhTfnUDx2bneAcEzGxvKb2dGh3uM SAj4r02KL2GLp+JbbXsPDL+BYsoe31+LqKttpfA2m5/93yPVp1YuzEyzk224zLan0ZeoD7IFImk k/bQj1S+BuloE6QEbD4yeb1hiMEFzusBrWlIAIftownBc85SXHTplbDLj6QX0s1dw4w== X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125231oal.1.1714147961418; Fri, 26 Apr 2024 09:12:41 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFKK09FSsz1w18C9O+QSKywaneNtUpj/aPvoeb+SOH3u9egTJYXPSkxUgqSN3BOrRHAMYNm3w== X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125169oal.1.1714147960484; Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Received: from x1n (pool-99-254-121-117.cpe.net.cable.rogers.com. [99.254.121.117]) by smtp.gmail.com with ESMTPSA id m6-20020ac807c6000000b00434fd7d6d00sm8007149qth.2.2024.04.26.09.12.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Date: Fri, 26 Apr 2024 12:12:32 -0400 From: Peter Xu To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mike Rapoport , Jason Gunthorpe , John Hubbard , linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions Message-ID: References: <20240402125516.223131-1-david@redhat.com> <20240402125516.223131-2-david@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240426_091245_507350_E6739124 X-CRM114-Status: GOOD ( 43.95 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Apr 26, 2024 at 09:44:58AM -0400, Peter Xu wrote: > On Fri, Apr 26, 2024 at 09:17:47AM +0200, David Hildenbrand wrote: > > On 02.04.24 14:55, David Hildenbrand wrote: > > > Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename > > > all relevant internal functions to start with "gup_fast", to make it > > > clearer that this is not ordinary GUP. The current mixture of > > > "lockless", "gup" and "gup_fast" is confusing. > > > > > > Further, avoid the term "huge" when talking about a "leaf" -- for > > > example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the > > > "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that > > > stays. > > > > > > What remains is the "external" interface: > > > * get_user_pages_fast_only() > > > * get_user_pages_fast() > > > * pin_user_pages_fast() > > > > > > The high-level internal functions for GUP-fast (+slow fallback) are now: > > > * internal_get_user_pages_fast() -> gup_fast_fallback() > > > * lockless_pages_from_mm() -> gup_fast() > > > > > > The basic GUP-fast walker functions: > > > * gup_pgd_range() -> gup_fast_pgd_range() > > > * gup_p4d_range() -> gup_fast_p4d_range() > > > * gup_pud_range() -> gup_fast_pud_range() > > > * gup_pmd_range() -> gup_fast_pmd_range() > > > * gup_pte_range() -> gup_fast_pte_range() > > > * gup_huge_pgd() -> gup_fast_pgd_leaf() > > > * gup_huge_pud() -> gup_fast_pud_leaf() > > > * gup_huge_pmd() -> gup_fast_pmd_leaf() > > > > > > The weird hugepd stuff: > > > * gup_huge_pd() -> gup_fast_hugepd() > > > * gup_hugepte() -> gup_fast_hugepte() > > > > I just realized that we end up calling these from follow_hugepd() as well. > > And something seems to be off, because gup_fast_hugepd() won't have the VMA > > even in the slow-GUP case to pass it to gup_must_unshare(). > > > > So these are GUP-fast functions and the terminology seem correct. But the > > usage from follow_hugepd() is questionable, > > > > commit a12083d721d703f985f4403d6b333cc449f838f6 > > Author: Peter Xu > > Date: Wed Mar 27 11:23:31 2024 -0400 > > > > mm/gup: handle hugepd for follow_page() > > > > > > states "With previous refactors on fast-gup gup_huge_pd(), most of the code > > can be leveraged", which doesn't look quite true just staring the the > > gup_must_unshare() call where we don't pass the VMA. Also, > > "unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense for > > slow GUP ... > > Yes it's not needed, just doesn't look worthwhile to put another helper on > top just for this. I mentioned this in the commit message here: > > There's something not needed for follow page, for example, gup_hugepte() > tries to detect pgtable entry change which will never happen with slow > gup (which has the pgtable lock held), but that's not a problem to check. > > > > > @Peter, any insights? > > However I think we should pass vma in for sure, I guess I overlooked that, > and it didn't expose in my tests too as I probably missed ./cow. > > I'll prepare a separate patch on top of this series and the gup-fast rename > patches (I saw this one just reached mm-stable), and I'll see whether I can > test it too if I can find a Power system fast enough. I'll probably drop > the "fast" in the hugepd function names too. Hmm, so when I enable 2M hugetlb I found ./cow is even failing on x86. # ./cow | grep -B1 "not ok" # [RUN] vmsplice() + unmap in child ... with hugetlb (2048 kB) not ok 161 No leak from parent into child -- # [RUN] vmsplice() + unmap in child with mprotect() optimization ... with hugetlb (2048 kB) not ok 215 No leak from parent into child -- # [RUN] vmsplice() before fork(), unmap in parent after fork() ... with hugetlb (2048 kB) not ok 269 No leak from child into parent -- # [RUN] vmsplice() + unmap in parent after fork() ... with hugetlb (2048 kB) not ok 323 No leak from child into parent And it looks like it was always failing.. perhaps since the start? We didn't do the same on hugetlb v.s. normal anon from that regard on the vmsplice() fix. I drafted a patch to allow refcount>1 detection as the same, then all tests pass for me, as below. David, I'd like to double check with you before I post anything: is that your intention to do so when working on the R/O pinning or not? Thanks, ========= >From 7300c249738dadda1457c755b597c1551dfe8dc6 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 26 Apr 2024 11:41:12 -0400 Subject: [PATCH] mm/hugetlb: Fix vmsplice case on memory leak once more Signed-off-by: Peter Xu --- mm/hugetlb.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 417fc5cdb6ee..1ca102013561 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5961,10 +5961,13 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, retry_avoidcopy: /* - * If no-one else is actually using this page, we're the exclusive - * owner and can reuse this page. + * If the page is marked exlusively owned (e.g. longterm pinned), + * we can reuse it. Otherwise if no-one else is using this page, + * we can savely set the exclusive bit and reuse it. */ - if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) { + if (folio_test_anon(old_folio) && + (PageAnonExclusive(&old_folio->page) || + folio_ref_count(old_folio) == 1)) { if (!PageAnonExclusive(&old_folio->page)) { folio_move_anon_rmap(old_folio, vma); SetPageAnonExclusive(&old_folio->page); -- 2.44.0 -- Peter Xu _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 942ACC4345F for ; Fri, 26 Apr 2024 16:13:36 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=iaVBsi9+; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=iaVBsi9+; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4VQySv0tPwz3dWK for ; Sat, 27 Apr 2024 02:13:35 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=iaVBsi9+; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=iaVBsi9+; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.129.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=peterx@redhat.com; receiver=lists.ozlabs.org) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4VQyS06DBSz3cXL for ; Sat, 27 Apr 2024 02:12:48 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714147964; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=iaVBsi9+KvAPRxFNS7Tpx2ZfTKHOwWJXU8AR5ITqSqRR1neFprAUhkGAWqITtivyad7jyz wUdKxC1jXCM+keMcB0kWSmQV9WwfgfXFxEvbBOHRH4WD9VYWqzMRDkfiDq77AqN3QHPy+B aVsdPHVQgN3Of9mzpMc6Vj7bR9Yvhk0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714147964; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=iaVBsi9+KvAPRxFNS7Tpx2ZfTKHOwWJXU8AR5ITqSqRR1neFprAUhkGAWqITtivyad7jyz wUdKxC1jXCM+keMcB0kWSmQV9WwfgfXFxEvbBOHRH4WD9VYWqzMRDkfiDq77AqN3QHPy+B aVsdPHVQgN3Of9mzpMc6Vj7bR9Yvhk0= Received: from mail-oo1-f72.google.com (mail-oo1-f72.google.com [209.85.161.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-251-Pz7GR7mCMVq92MO6YbS34g-1; Fri, 26 Apr 2024 12:12:42 -0400 X-MC-Unique: Pz7GR7mCMVq92MO6YbS34g-1 Received: by mail-oo1-f72.google.com with SMTP id 006d021491bc7-5aa35f3393bso594195eaf.1 for ; Fri, 26 Apr 2024 09:12:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714147962; x=1714752762; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=fCJ1aa6PHr7Kkg9rpTbbZSBI56YpTnlndIPJPszFGq2fnyfZmvFSEbvORT+omzT5Ij dnDEhkzquJSQPERGUbp8bCE8nRRLnPhRY8U+PkxvMFiRJI3KeZo1FIppbZITfeEYo9xE Nls665dO7jeP94z6qta2X+6S8Y3OAMJ9I5inFREtrdpPCz/bKGqyalZN2tgBLMMDOj4w 87nw5DLG9Wni9YCcGllrspS1XS9IOWzcirh8d0d8vkOCg1UnICpKiIhFLUNYWxXmwkl/ bdCuBD6hj9/fVODSZFA4gUeFdrscUEnDOzqG7K0Fe+bVYOCI3SjkdhGpoaDfY90ijYga efOg== X-Forwarded-Encrypted: i=1; AJvYcCXN4n9OS7pKQsKUZwVp8oIAZW67JdK82qbYDGpidHm/f9IrYCbnYAnN/raUy01tNi8qkdX8ycP1cIPZVfMUCGH612M3c1q8E5tB+tGh1A== X-Gm-Message-State: AOJu0YyxHcIVgCB9wlqc5Cvv3cH7vA9OgGp6skKSKFm3nqGdf6mM3yRe HhOgSox/Ux/8bocLIl4+kxCvyHVNWQaweLVvq5z5WJNNLbfRBtzKYebWDSpJ6D2u+766GuXrKTg auLsUDDqzTo4wQepo+VXFPDl5VDqk3dle/XwT8xVBJc7Plpw86w5OOnrHT5m4wVo= X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125232oal.1.1714147961419; Fri, 26 Apr 2024 09:12:41 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFKK09FSsz1w18C9O+QSKywaneNtUpj/aPvoeb+SOH3u9egTJYXPSkxUgqSN3BOrRHAMYNm3w== X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125169oal.1.1714147960484; Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Received: from x1n (pool-99-254-121-117.cpe.net.cable.rogers.com. [99.254.121.117]) by smtp.gmail.com with ESMTPSA id m6-20020ac807c6000000b00434fd7d6d00sm8007149qth.2.2024.04.26.09.12.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Date: Fri, 26 Apr 2024 12:12:32 -0400 From: Peter Xu To: David Hildenbrand Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions Message-ID: References: <20240402125516.223131-1-david@redhat.com> <20240402125516.223131-2-david@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, loongarch@lists.linux.dev, linux-sh@vger.kernel.org, John Hubbard , x86@kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Jason Gunthorpe , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, Mike Rapoport Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Apr 26, 2024 at 09:44:58AM -0400, Peter Xu wrote: > On Fri, Apr 26, 2024 at 09:17:47AM +0200, David Hildenbrand wrote: > > On 02.04.24 14:55, David Hildenbrand wrote: > > > Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename > > > all relevant internal functions to start with "gup_fast", to make it > > > clearer that this is not ordinary GUP. The current mixture of > > > "lockless", "gup" and "gup_fast" is confusing. > > > > > > Further, avoid the term "huge" when talking about a "leaf" -- for > > > example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the > > > "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that > > > stays. > > > > > > What remains is the "external" interface: > > > * get_user_pages_fast_only() > > > * get_user_pages_fast() > > > * pin_user_pages_fast() > > > > > > The high-level internal functions for GUP-fast (+slow fallback) are now: > > > * internal_get_user_pages_fast() -> gup_fast_fallback() > > > * lockless_pages_from_mm() -> gup_fast() > > > > > > The basic GUP-fast walker functions: > > > * gup_pgd_range() -> gup_fast_pgd_range() > > > * gup_p4d_range() -> gup_fast_p4d_range() > > > * gup_pud_range() -> gup_fast_pud_range() > > > * gup_pmd_range() -> gup_fast_pmd_range() > > > * gup_pte_range() -> gup_fast_pte_range() > > > * gup_huge_pgd() -> gup_fast_pgd_leaf() > > > * gup_huge_pud() -> gup_fast_pud_leaf() > > > * gup_huge_pmd() -> gup_fast_pmd_leaf() > > > > > > The weird hugepd stuff: > > > * gup_huge_pd() -> gup_fast_hugepd() > > > * gup_hugepte() -> gup_fast_hugepte() > > > > I just realized that we end up calling these from follow_hugepd() as well. > > And something seems to be off, because gup_fast_hugepd() won't have the VMA > > even in the slow-GUP case to pass it to gup_must_unshare(). > > > > So these are GUP-fast functions and the terminology seem correct. But the > > usage from follow_hugepd() is questionable, > > > > commit a12083d721d703f985f4403d6b333cc449f838f6 > > Author: Peter Xu > > Date: Wed Mar 27 11:23:31 2024 -0400 > > > > mm/gup: handle hugepd for follow_page() > > > > > > states "With previous refactors on fast-gup gup_huge_pd(), most of the code > > can be leveraged", which doesn't look quite true just staring the the > > gup_must_unshare() call where we don't pass the VMA. Also, > > "unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense for > > slow GUP ... > > Yes it's not needed, just doesn't look worthwhile to put another helper on > top just for this. I mentioned this in the commit message here: > > There's something not needed for follow page, for example, gup_hugepte() > tries to detect pgtable entry change which will never happen with slow > gup (which has the pgtable lock held), but that's not a problem to check. > > > > > @Peter, any insights? > > However I think we should pass vma in for sure, I guess I overlooked that, > and it didn't expose in my tests too as I probably missed ./cow. > > I'll prepare a separate patch on top of this series and the gup-fast rename > patches (I saw this one just reached mm-stable), and I'll see whether I can > test it too if I can find a Power system fast enough. I'll probably drop > the "fast" in the hugepd function names too. Hmm, so when I enable 2M hugetlb I found ./cow is even failing on x86. # ./cow | grep -B1 "not ok" # [RUN] vmsplice() + unmap in child ... with hugetlb (2048 kB) not ok 161 No leak from parent into child -- # [RUN] vmsplice() + unmap in child with mprotect() optimization ... with hugetlb (2048 kB) not ok 215 No leak from parent into child -- # [RUN] vmsplice() before fork(), unmap in parent after fork() ... with hugetlb (2048 kB) not ok 269 No leak from child into parent -- # [RUN] vmsplice() + unmap in parent after fork() ... with hugetlb (2048 kB) not ok 323 No leak from child into parent And it looks like it was always failing.. perhaps since the start? We didn't do the same on hugetlb v.s. normal anon from that regard on the vmsplice() fix. I drafted a patch to allow refcount>1 detection as the same, then all tests pass for me, as below. David, I'd like to double check with you before I post anything: is that your intention to do so when working on the R/O pinning or not? Thanks, ========= >From 7300c249738dadda1457c755b597c1551dfe8dc6 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 26 Apr 2024 11:41:12 -0400 Subject: [PATCH] mm/hugetlb: Fix vmsplice case on memory leak once more Signed-off-by: Peter Xu --- mm/hugetlb.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 417fc5cdb6ee..1ca102013561 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5961,10 +5961,13 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, retry_avoidcopy: /* - * If no-one else is actually using this page, we're the exclusive - * owner and can reuse this page. + * If the page is marked exlusively owned (e.g. longterm pinned), + * we can reuse it. Otherwise if no-one else is using this page, + * we can savely set the exclusive bit and reuse it. */ - if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) { + if (folio_test_anon(old_folio) && + (PageAnonExclusive(&old_folio->page) || + folio_ref_count(old_folio) == 1)) { if (!PageAnonExclusive(&old_folio->page)) { folio_move_anon_rmap(old_folio, vma); SetPageAnonExclusive(&old_folio->page); -- 2.44.0 -- Peter Xu From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CB8F5C4345F for ; Fri, 26 Apr 2024 16:13:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=03VGK4jB9wfBWe76wdMIdr3d1ZIoQBjin59SwRtbiOk=; b=zYrFpkVIey9P7K FgDEMZ82k3VFLIqQQBsi3mFg9EJUOSzjyf3yWkKLJsGU+5m463efnsWMSXHaENAkHKm2cehlHM7/7 JzPjyKjoZf5oPOAJSlCBkp12gAm8S335+d25bSth41pjUCPT604mXpII7jM0KuN5p4ZwFuReYKKSi NLAdX7jRk+8fIgWR+Tg+GEJ4fP8k38MD1alqveuZE0HaMZT8vUM92o9HwfI9OddEj5jKddZcGaLcK hqa2fYolzAOxPsK0dsnwY61c4pP3rZpK5FNi7CLlfrHMKWm7eBdttFJZHFYvVgwMZ/qaLxdz7/UKn NVk7+m97B6gzUDzOO9mQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0OBt-0000000DCg1-2iD9; Fri, 26 Apr 2024 16:12:49 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0OBp-0000000DCe6-1A3D for linux-arm-kernel@lists.infradead.org; Fri, 26 Apr 2024 16:12:47 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1714147963; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=LypP9JvOUwTJ+H67rwONo9wwRCDu7c4QosQU9i/xSC7EmmvETQP+nnNJgYw4vxqKKqI2rT p6+9SIKxj7B8VcSqnaf+5p3cIiRNM+TEH2OxbP52yBiEALFUWqq9N6PaG46XJ+JZ/4ZpKC y8QXaCCaiIVIz4CAWLMaud9ezd13PoQ= Received: from mail-oo1-f69.google.com (mail-oo1-f69.google.com [209.85.161.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-14-f0jJjwP_O5iR2qpnzDpE3A-1; Fri, 26 Apr 2024 12:12:42 -0400 X-MC-Unique: f0jJjwP_O5iR2qpnzDpE3A-1 Received: by mail-oo1-f69.google.com with SMTP id 006d021491bc7-5acdbf9d0c6so599619eaf.3 for ; Fri, 26 Apr 2024 09:12:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714147962; x=1714752762; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=eYUqEa4yY2qzSFoFdIvLcLWvg/98iZ7Cq/Vjg2cb5Pg=; b=SUQOyx7+cfZC0Mf+AFRsiP/BfPlKstPKnr7Fww8ZtNGjKv6Ex8jIjH/eEQZ1ovFu1D uaL2mfte46LF7VAFo9WqJmV0/+IQdDhk5BXinCWrFK7YwrPnGQx7YBIDDG6gHOVsJTN+ qs5MvV2REtvxcVTtPFDzqLj5S+ziwbSIX2tWpNND+OMlIYWa+1UBmvk2T6hRq6gTs7sk MNmv6ifcdg2fpHe/ESb1Xg3MIFpvbuzjUjaRPTUixzIB087znu/zMFTrbxhNHmTlFf5u klGP7fkM78fMLRO4MspHAtB+kKxLOhtXVv/0gUuTXA4lNzMqcBe4NVvKU7M6QoibKQnV a+iw== X-Forwarded-Encrypted: i=1; AJvYcCXFzCCizCIuCRSu2fUzje2c2zrOF05QKUd4fYlloxBJfow7mqO+LOsleldGgjKArYizcjfrdJfL7Yt9TyNyZ5G+YgM95gKufKIWFyyaSiuZRfJeg7U= X-Gm-Message-State: AOJu0YwH/3tZpg5gV4igcZVO11k2PPXCZGUIZ+8zu7PLkjigO+/lMal+ tGNWQAvpQaYK5p/HBsa9XX3Y+WOQFoxc6mVX73LzRg6A8Tl047SPn5YR6WmMP8FGr0IIhj0nT/R usoGPgbj+cvoFxMfgC3fTBAXbQGGmhgsAi8/C+3H0qYQU3K3kwIo/iZxK3f6ChARy9tVye0sQ X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125228oal.1.1714147961420; Fri, 26 Apr 2024 09:12:41 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFKK09FSsz1w18C9O+QSKywaneNtUpj/aPvoeb+SOH3u9egTJYXPSkxUgqSN3BOrRHAMYNm3w== X-Received: by 2002:a05:6870:a40f:b0:235:3e97:ed24 with SMTP id m15-20020a056870a40f00b002353e97ed24mr3125169oal.1.1714147960484; Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Received: from x1n (pool-99-254-121-117.cpe.net.cable.rogers.com. [99.254.121.117]) by smtp.gmail.com with ESMTPSA id m6-20020ac807c6000000b00434fd7d6d00sm8007149qth.2.2024.04.26.09.12.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Apr 2024 09:12:40 -0700 (PDT) Date: Fri, 26 Apr 2024 12:12:32 -0400 From: Peter Xu To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mike Rapoport , Jason Gunthorpe , John Hubbard , linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions Message-ID: References: <20240402125516.223131-1-david@redhat.com> <20240402125516.223131-2-david@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240426_091245_507666_C87C1915 X-CRM114-Status: GOOD ( 45.20 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Apr 26, 2024 at 09:44:58AM -0400, Peter Xu wrote: > On Fri, Apr 26, 2024 at 09:17:47AM +0200, David Hildenbrand wrote: > > On 02.04.24 14:55, David Hildenbrand wrote: > > > Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename > > > all relevant internal functions to start with "gup_fast", to make it > > > clearer that this is not ordinary GUP. The current mixture of > > > "lockless", "gup" and "gup_fast" is confusing. > > > > > > Further, avoid the term "huge" when talking about a "leaf" -- for > > > example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the > > > "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that > > > stays. > > > > > > What remains is the "external" interface: > > > * get_user_pages_fast_only() > > > * get_user_pages_fast() > > > * pin_user_pages_fast() > > > > > > The high-level internal functions for GUP-fast (+slow fallback) are now: > > > * internal_get_user_pages_fast() -> gup_fast_fallback() > > > * lockless_pages_from_mm() -> gup_fast() > > > > > > The basic GUP-fast walker functions: > > > * gup_pgd_range() -> gup_fast_pgd_range() > > > * gup_p4d_range() -> gup_fast_p4d_range() > > > * gup_pud_range() -> gup_fast_pud_range() > > > * gup_pmd_range() -> gup_fast_pmd_range() > > > * gup_pte_range() -> gup_fast_pte_range() > > > * gup_huge_pgd() -> gup_fast_pgd_leaf() > > > * gup_huge_pud() -> gup_fast_pud_leaf() > > > * gup_huge_pmd() -> gup_fast_pmd_leaf() > > > > > > The weird hugepd stuff: > > > * gup_huge_pd() -> gup_fast_hugepd() > > > * gup_hugepte() -> gup_fast_hugepte() > > > > I just realized that we end up calling these from follow_hugepd() as well. > > And something seems to be off, because gup_fast_hugepd() won't have the VMA > > even in the slow-GUP case to pass it to gup_must_unshare(). > > > > So these are GUP-fast functions and the terminology seem correct. But the > > usage from follow_hugepd() is questionable, > > > > commit a12083d721d703f985f4403d6b333cc449f838f6 > > Author: Peter Xu > > Date: Wed Mar 27 11:23:31 2024 -0400 > > > > mm/gup: handle hugepd for follow_page() > > > > > > states "With previous refactors on fast-gup gup_huge_pd(), most of the code > > can be leveraged", which doesn't look quite true just staring the the > > gup_must_unshare() call where we don't pass the VMA. Also, > > "unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense for > > slow GUP ... > > Yes it's not needed, just doesn't look worthwhile to put another helper on > top just for this. I mentioned this in the commit message here: > > There's something not needed for follow page, for example, gup_hugepte() > tries to detect pgtable entry change which will never happen with slow > gup (which has the pgtable lock held), but that's not a problem to check. > > > > > @Peter, any insights? > > However I think we should pass vma in for sure, I guess I overlooked that, > and it didn't expose in my tests too as I probably missed ./cow. > > I'll prepare a separate patch on top of this series and the gup-fast rename > patches (I saw this one just reached mm-stable), and I'll see whether I can > test it too if I can find a Power system fast enough. I'll probably drop > the "fast" in the hugepd function names too. Hmm, so when I enable 2M hugetlb I found ./cow is even failing on x86. # ./cow | grep -B1 "not ok" # [RUN] vmsplice() + unmap in child ... with hugetlb (2048 kB) not ok 161 No leak from parent into child -- # [RUN] vmsplice() + unmap in child with mprotect() optimization ... with hugetlb (2048 kB) not ok 215 No leak from parent into child -- # [RUN] vmsplice() before fork(), unmap in parent after fork() ... with hugetlb (2048 kB) not ok 269 No leak from child into parent -- # [RUN] vmsplice() + unmap in parent after fork() ... with hugetlb (2048 kB) not ok 323 No leak from child into parent And it looks like it was always failing.. perhaps since the start? We didn't do the same on hugetlb v.s. normal anon from that regard on the vmsplice() fix. I drafted a patch to allow refcount>1 detection as the same, then all tests pass for me, as below. David, I'd like to double check with you before I post anything: is that your intention to do so when working on the R/O pinning or not? Thanks, ========= >From 7300c249738dadda1457c755b597c1551dfe8dc6 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Fri, 26 Apr 2024 11:41:12 -0400 Subject: [PATCH] mm/hugetlb: Fix vmsplice case on memory leak once more Signed-off-by: Peter Xu --- mm/hugetlb.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 417fc5cdb6ee..1ca102013561 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5961,10 +5961,13 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, retry_avoidcopy: /* - * If no-one else is actually using this page, we're the exclusive - * owner and can reuse this page. + * If the page is marked exlusively owned (e.g. longterm pinned), + * we can reuse it. Otherwise if no-one else is using this page, + * we can savely set the exclusive bit and reuse it. */ - if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) { + if (folio_test_anon(old_folio) && + (PageAnonExclusive(&old_folio->page) || + folio_ref_count(old_folio) == 1)) { if (!PageAnonExclusive(&old_folio->page)) { folio_move_anon_rmap(old_folio, vma); SetPageAnonExclusive(&old_folio->page); -- 2.44.0 -- Peter Xu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel