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Sun, 27 Apr 2025 13:35:46 -0400 X-MC-Unique: _InogbtzN7WQV-c7OXCMDw-1 X-Mimecast-MFC-AGG-ID: _InogbtzN7WQV-c7OXCMDw_1745775344 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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 mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 587421800263; Sun, 27 Apr 2025 17:35:42 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.18]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 5D28419560A3; Sun, 27 Apr 2025 17:35:35 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 27 Apr 2025 19:35:04 +0200 (CEST) Date: Sun, 27 Apr 2025 19:34:56 +0200 From: Oleg Nesterov To: Jiri Olsa Cc: Peter Zijlstra , Andrii Nakryiko , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Masami Hiramatsu , Alan Maguire , David Laight , Thomas =?iso-8859-1?Q?Wei=DFschuh?= , Ingo Molnar Subject: Re: [PATCH perf/core 08/22] uprobes/x86: Add mapping for optimized uprobe trampolines Message-ID: <20250427173456.GB27775@redhat.com> References: <20250421214423.393661-1-jolsa@kernel.org> <20250421214423.393661-9-jolsa@kernel.org> <20250427145606.GC9350@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250427145606.GC9350@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 On 04/27, Oleg Nesterov wrote: > > On 04/21, Jiri Olsa wrote: > > > > +static unsigned long find_nearest_page(unsigned long vaddr) > > +{ > > + struct vm_area_struct *vma, *prev = NULL; > > + unsigned long prev_vm_end = PAGE_SIZE; > > + VMA_ITERATOR(vmi, current->mm, 0); > > + > > + vma = vma_next(&vmi); > > + while (vma) { > > + if (prev) > > + prev_vm_end = prev->vm_end; > > + if (vma->vm_start - prev_vm_end >= PAGE_SIZE) { > > + if (is_reachable_by_call(prev_vm_end, vaddr)) > > + return prev_vm_end; > > + if (is_reachable_by_call(vma->vm_start - PAGE_SIZE, vaddr)) > > + return vma->vm_start - PAGE_SIZE; > > + } > > + prev = vma; > > + vma = vma_next(&vmi); > > + } > > + > > + return 0; > > +} > > This can be simplified afaics... We don't really need prev, and we can > use for_each_vma(), > > static unsigned long find_nearest_page(unsigned long vaddr) > { > struct vm_area_struct *vma; > unsigned long prev_vm_end = PAGE_SIZE; > VMA_ITERATOR(vmi, current->mm, 0); > > for_each_vma(vmi, vma) { > if (vma->vm_start - prev_vm_end >= PAGE_SIZE) { > if (is_reachable_by_call(prev_vm_end, vaddr)) > return prev_vm_end; > if (is_reachable_by_call(vma->vm_start - PAGE_SIZE, vaddr)) > return vma->vm_start - PAGE_SIZE; > } > prev_vm_end = vma->vm_end; > } > > return 0; > } Either way it doesn't look nice. If nothing else, we should respect vm_start/end_gap(vma). Can't we do something like struct vm_unmapped_area_info info = {}; info.length = PAGE_SIZE; info.low_limit = vaddr - INT_MIN + 5; info.high_limit = vaddr + INT_MAX; info.flags = VM_UNMAPPED_AREA_TOPDOWN; // makes sense? return vm_unmapped_area(&info); instead ? Oleg.