From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757075Ab2DKKmv (ORCPT ); Wed, 11 Apr 2012 06:42:51 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:39168 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755094Ab2DKKmu (ORCPT ); Wed, 11 Apr 2012 06:42:50 -0400 From: Srikar Dronamraju To: Peter Zijlstra , Ingo Molnar Cc: Andrew Morton , Linus Torvalds , Ananth N Mavinakayanahalli , Jim Keniston , LKML , Linux-mm , Oleg Nesterov , Andi Kleen , Christoph Hellwig , Steven Rostedt , Arnaldo Carvalho de Melo , Masami Hiramatsu , Thomas Gleixner , Anton Arapov Date: Wed, 11 Apr 2012 16:05:27 +0530 Message-Id: <20120411103527.23245.9835.sendpatchset@srdronam.in.ibm.com> In-Reply-To: <20120411103516.23245.2700.sendpatchset@srdronam.in.ibm.com> References: <20120411103516.23245.2700.sendpatchset@srdronam.in.ibm.com> Subject: [PATCH 2/2] uprobes/core: Decrement uprobe count before the pages are unmapped x-cbid: 12041100-6102-0000-0000-00000138E804 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Srikar Dronamraju Uprobes has a hook(uprobe_munmap) in unmap path to keep the uprobes count sane. In the exit path this hook gets called in unlink_file_vma. However by the time unlink_file_vma is called, the pages would have been unmapped (unmap_vmas) and the rss_stat counts accounted (zap_pte_range). If the exiting process has probepoints, uprobe_munmap checks if the breakpoint instruction was around before decrementing the probe count. This results in a filebacked page being reread by uprobe_munmap and hence it does not find the breakpoint. This patch fixes this problem by moving the hook to unmap_single_vma. Since unmap_single_vma may not unmap the complete vma, add start and end parameters to uprobe_munmap. This bug became apparent courtesy commit c3f0327f8e9d7. Signed-off-by: Srikar Dronamraju --- include/linux/uprobes.h | 5 +++-- kernel/events/uprobes.c | 4 ++-- mm/memory.c | 3 +++ mm/mmap.c | 8 ++++---- 4 files changed, 12 insertions(+), 8 deletions(-) diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index d594d3b..efe4b33 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -107,7 +107,7 @@ extern bool __weak is_swbp_insn(uprobe_opcode_t *insn); extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); extern int uprobe_mmap(struct vm_area_struct *vma); -extern void uprobe_munmap(struct vm_area_struct *vma); +extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end); extern void uprobe_free_utask(struct task_struct *t); extern void uprobe_copy_process(struct task_struct *t); extern unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs); @@ -134,7 +134,8 @@ static inline int uprobe_mmap(struct vm_area_struct *vma) { return 0; } -static inline void uprobe_munmap(struct vm_area_struct *vma) +static inline void +uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) { } static inline void uprobe_notify_resume(struct pt_regs *regs) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index c5caeec..985be4d 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1112,7 +1112,7 @@ int uprobe_mmap(struct vm_area_struct *vma) /* * Called in context of a munmap of a vma. */ -void uprobe_munmap(struct vm_area_struct *vma) +void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) { struct list_head tmp_list; struct uprobe *uprobe, *u; @@ -1138,7 +1138,7 @@ void uprobe_munmap(struct vm_area_struct *vma) list_del(&uprobe->pending_list); vaddr = vma_address(vma, uprobe->offset); - if (vaddr >= vma->vm_start && vaddr < vma->vm_end) { + if (vaddr >= start && vaddr < end) { /* * An unregister could have removed the probe before * unmap. So check before we decrement the count. diff --git a/mm/memory.c b/mm/memory.c index 6105f47..bf8b403 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1307,6 +1307,9 @@ static void unmap_single_vma(struct mmu_gather *tlb, if (end <= vma->vm_start) return; + if (vma->vm_file) + uprobe_munmap(vma, start, end); + if (vma->vm_flags & VM_ACCOUNT) *nr_accounted += (end - start) >> PAGE_SHIFT; diff --git a/mm/mmap.c b/mm/mmap.c index b17a39f..15c21a1 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -218,7 +218,6 @@ void unlink_file_vma(struct vm_area_struct *vma) mutex_lock(&mapping->i_mmap_mutex); __remove_shared_vm_struct(vma, file, mapping); mutex_unlock(&mapping->i_mmap_mutex); - uprobe_munmap(vma); } } @@ -548,10 +547,11 @@ again: remove_next = 1 + (end > next->vm_end); mapping = file->f_mapping; if (!(vma->vm_flags & VM_NONLINEAR)) { root = &mapping->i_mmap; - uprobe_munmap(vma); + uprobe_munmap(vma, vma->vm_start, vma->vm_end); if (adjust_next) - uprobe_munmap(next); + uprobe_munmap(next, next->vm_start, + next->vm_end); } mutex_lock(&mapping->i_mmap_mutex); @@ -632,7 +632,7 @@ again: remove_next = 1 + (end > next->vm_end); if (remove_next) { if (file) { - uprobe_munmap(next); + uprobe_munmap(next, next->vm_start, next->vm_end); fput(file); if (next->vm_flags & VM_EXECUTABLE) removed_exe_file_vma(mm);