From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 8BCC46B025F for ; Tue, 19 Dec 2017 09:42:14 -0500 (EST) Received: by mail-wr0-f198.google.com with SMTP id y23so11441634wra.16 for ; Tue, 19 Dec 2017 06:42:14 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id p72si1304214wmb.227.2017.12.19.06.42.13 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 19 Dec 2017 06:42:13 -0800 (PST) Date: Tue, 19 Dec 2017 15:42:11 +0100 From: Michal Hocko Subject: Re: [PATCH] Provide useful debugging information for VM_BUG Message-ID: <20171219144211.GY2787@dhcp22.suse.cz> References: <20171219133236.GE13680@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171219133236.GE13680@bombadil.infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox Cc: linux-mm@kvack.org, "Tobin C. Harding" , kernel-hardening@lists.openwall.com On Tue 19-12-17 05:32:36, Matthew Wilcox wrote: > > From: Matthew Wilcox > > With the recent addition of hashed kernel pointers, places which need > to produce useful debug output have to specify %px, not %p. This patch > fixes all the VM debug to use %px. This is appropriate because it's > debug output that the user should never be able to trigger, and kernel > developers need to see the actual pointers. Agreed. This is essentially a BUG_ON so we shouldn't hide information. I am just wondering why %px rather than %lx (like __show_regs e.g.)? > Signed-off-by: Matthew Wilcox Acked-by: Michal Hocko > diff --git a/mm/debug.c b/mm/debug.c > index d947f3e03b0d..56e2d9125ea5 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -50,7 +50,7 @@ void __dump_page(struct page *page, const char *reason) > */ > int mapcount = PageSlab(page) ? 0 : page_mapcount(page); > > - pr_emerg("page:%p count:%d mapcount:%d mapping:%p index:%#lx", > + pr_emerg("page:%px count:%d mapcount:%d mapping:%px index:%#lx", > page, page_ref_count(page), mapcount, > page->mapping, page_to_pgoff(page)); > if (PageCompound(page)) > @@ -69,7 +69,7 @@ void __dump_page(struct page *page, const char *reason) > > #ifdef CONFIG_MEMCG > if (page->mem_cgroup) > - pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup); > + pr_alert("page->mem_cgroup:%px\n", page->mem_cgroup); > #endif > } > > @@ -84,10 +84,10 @@ EXPORT_SYMBOL(dump_page); > > void dump_vma(const struct vm_area_struct *vma) > { > - pr_emerg("vma %p start %p end %p\n" > - "next %p prev %p mm %p\n" > - "prot %lx anon_vma %p vm_ops %p\n" > - "pgoff %lx file %p private_data %p\n" > + pr_emerg("vma %px start %px end %px\n" > + "next %px prev %px mm %px\n" > + "prot %lx anon_vma %px vm_ops %px\n" > + "pgoff %lx file %px private_data %px\n" > "flags: %#lx(%pGv)\n", > vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next, > vma->vm_prev, vma->vm_mm, > @@ -100,27 +100,27 @@ EXPORT_SYMBOL(dump_vma); > > void dump_mm(const struct mm_struct *mm) > { > - pr_emerg("mm %p mmap %p seqnum %d task_size %lu\n" > + pr_emerg("mm %px mmap %px seqnum %d task_size %lu\n" > #ifdef CONFIG_MMU > - "get_unmapped_area %p\n" > + "get_unmapped_area %px\n" > #endif > "mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n" > - "pgd %p mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n" > + "pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n" > "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n" > "pinned_vm %lx data_vm %lx exec_vm %lx stack_vm %lx\n" > "start_code %lx end_code %lx start_data %lx end_data %lx\n" > "start_brk %lx brk %lx start_stack %lx\n" > "arg_start %lx arg_end %lx env_start %lx env_end %lx\n" > - "binfmt %p flags %lx core_state %p\n" > + "binfmt %px flags %lx core_state %px\n" > #ifdef CONFIG_AIO > - "ioctx_table %p\n" > + "ioctx_table %px\n" > #endif > #ifdef CONFIG_MEMCG > - "owner %p " > + "owner %px " > #endif > - "exe_file %p\n" > + "exe_file %px\n" > #ifdef CONFIG_MMU_NOTIFIER > - "mmu_notifier_mm %p\n" > + "mmu_notifier_mm %px\n" > #endif > #ifdef CONFIG_NUMA_BALANCING > "numa_next_scan %lu numa_scan_offset %lu numa_scan_seq %d\n" > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org