From nobody Tue Apr 7 10:39:53 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DB77ECAAD8 for ; Mon, 29 Aug 2022 21:27:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229941AbiH2V1t (ORCPT ); Mon, 29 Aug 2022 17:27:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229918AbiH2V1H (ORCPT ); Mon, 29 Aug 2022 17:27:07 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFFB49F0DA for ; Mon, 29 Aug 2022 14:26:19 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id x25-20020aa79199000000b005358eeebf49so3609848pfa.17 for ; Mon, 29 Aug 2022 14:26:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc; bh=3FeDd/uESQnEyJqRWNnPK+iT++ObIkcBX2+m7Yxyetk=; b=WuXmy7spYby6FKlYZxVkneAX6CYLeedEW25AaCdm5U/xwDtXPaTsukbnW+BREr3wmK Yp+DdB6epKs/SB7JvycD5yPQfOWs3SBJlayjVM1bzBPF4xDdscUUlmQ491HoasCmixWz EDQApyvlKJ0m9j6IZ5Bl5eAvYAMUvQ5PzTt+MmJPi2OMUuj7wlttfCVr1jtd4buEfno/ mHPpjk9OptKM0QuTB8OPa5JPYvPxCHU8q8PlG/PC9yFoVmLZ3eeWZBp1XntU6iG84/rA BgcQG1UC8Z471LrYLx/b3SNnNzdfHV9f4k2uE0RZvNOL2F/Wod5mOLtISQc7G5F1GR1Y 7dZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc; bh=3FeDd/uESQnEyJqRWNnPK+iT++ObIkcBX2+m7Yxyetk=; b=dY/pvieqME8M6CCzMo8hHMq7UMxLZQz+RzdFj3I9WPsEKkTL2pBTpuNCHOtykGYKoF 9he7Q7AfIWt82nXkScTsr75fPHfpK2fCfyGSWnSrv+Laoudi1gs8/YVsCiIqABOXguH9 kGab+DKH0iMqPmgE/qMwIZ8TPiAKkkCwhNjV9+b41E4F2QkfaTxdxASjDAO9XPxbZuAc PhzATRSSFiJoIiADifggCgmhI7dvCXWgg4p+8DIPFjF17WdnaQAlwOWuqBn6dxZrgBLw 0bER5sC8eH38bp8WDDNtj13hvcSmdYv0V1f1kuQcQ0StgCCcrZxOL7eR09fl27Uns8+8 5VRg== X-Gm-Message-State: ACgBeo3VhfVFg8TL4yf7UsxbKF8+2ViNxobEb6lUPLxuZ0KGcsbj5Q5T FpHq09vUWa2HlnXbvmW0uc7DkmZxwSc= X-Google-Smtp-Source: AA6agR65SMIHezE5eUhR7FLJy4sKjKwDRErJ8crUMropZEJrhJg/maBEVhsE6eunhKdLtoV+/pEsLbtUb5g= X-Received: from surenb-spec.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e30]) (user=surenb job=sendgmr) by 2002:a62:b519:0:b0:537:9723:5cf2 with SMTP id y25-20020a62b519000000b0053797235cf2mr18436343pfe.15.1661808377917; Mon, 29 Aug 2022 14:26:17 -0700 (PDT) Date: Mon, 29 Aug 2022 21:25:27 +0000 In-Reply-To: <20220829212531.3184856-1-surenb@google.com> Mime-Version: 1.0 References: <20220829212531.3184856-1-surenb@google.com> X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220829212531.3184856-25-surenb@google.com> Subject: [RFC PATCH 24/28] arm64/mm: try VMA lock-based page fault handling first From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, riel@surriel.com, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, surenb@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Attempt VMA lock-based page fault handling first, and fall back to the existing mmap_lock-based handling if that fails. Signed-off-by: Suren Baghdasaryan --- arch/arm64/mm/fault.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index c33f1fad2745..f05ce40ff32b 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -525,6 +525,9 @@ static int __kprobes do_page_fault(unsigned long far, u= nsigned long esr, unsigned long vm_flags; unsigned int mm_flags =3D FAULT_FLAG_DEFAULT; unsigned long addr =3D untagged_addr(far); +#ifdef CONFIG_PER_VMA_LOCK + struct vm_area_struct *vma; +#endif =20 if (kprobe_page_fault(regs, esr)) return 0; @@ -575,6 +578,36 @@ static int __kprobes do_page_fault(unsigned long far, = unsigned long esr, =20 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); =20 +#ifdef CONFIG_PER_VMA_LOCK + if (!(mm_flags & FAULT_FLAG_USER) || atomic_read(&mm->mm_users) =3D=3D 1) + goto lock_mmap; + + vma =3D find_and_lock_anon_vma(mm, addr); + if (!vma) + goto lock_mmap; + + if (!(vma->vm_flags & vm_flags)) { + vma_read_unlock(vma); + goto lock_mmap; + } + fault =3D handle_mm_fault(vma, addr & PAGE_MASK, + mm_flags | FAULT_FLAG_VMA_LOCK, regs); + vma_read_unlock(vma); + + if (!(fault & VM_FAULT_RETRY)) { + count_vm_vma_lock_event(VMA_LOCK_SUCCESS); + goto done; + } + count_vm_vma_lock_event(VMA_LOCK_RETRY); + + /* Quick path to respond to signals */ + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; + return 0; + } +lock_mmap: +#endif /* CONFIG_PER_VMA_LOCK */ /* * As per x86, we may deadlock here. However, since the kernel only * validly references user space from well defined areas of the code, @@ -618,6 +651,9 @@ static int __kprobes do_page_fault(unsigned long far, u= nsigned long esr, } mmap_read_unlock(mm); =20 +#ifdef CONFIG_PER_VMA_LOCK +done: +#endif /* * Handle the "normal" (no error) case first. */ --=20 2.37.2.672.g94769d06f0-goog