linux-kernel - Re: [PATCH uprobe, thp 2/4] uprobe: use original page when all uprobes are removed

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Message-ID: <F97FB4EB-3416-4BE7-9539-E58A3AD86874@fb.com>
Date:   Thu, 30 May 2019 17:18:43 +0000
From:   Song Liu <songliubraving@...com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
CC:     linux-kernel <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "namit@...are.com" <namit@...are.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "oleg@...hat.com" <oleg@...hat.com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "mhiramat@...nel.org" <mhiramat@...nel.org>,
        "matthew.wilcox@...cle.com" <matthew.wilcox@...cle.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        Kernel Team <Kernel-team@...com>,
        "william.kucharski@...cle.com" <william.kucharski@...cle.com>,
        "chad.mynhier@...cle.com" <chad.mynhier@...cle.com>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>
Subject: Re: [PATCH uprobe, thp 2/4] uprobe: use original page when all
 uprobes are removed



> On May 30, 2019, at 4:17 AM, Kirill A. Shutemov <kirill@...temov.name> wrote:
> 
> On Wed, May 29, 2019 at 02:20:47PM -0700, Song Liu wrote:
>> @@ -501,6 +512,20 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
>> 	copy_highpage(new_page, old_page);
>> 	copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
>> 
>> +	index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT;
>> +	orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, index);
>> +	if (orig_page) {
>> +		if (memcmp(page_address(orig_page),
>> +			   page_address(new_page), PAGE_SIZE) == 0) {
> 
> Does it work for highmem?

Good catch! I will fix it in v2. 

Thanks!
Song

> 
> 
> -- 
> Kirill A. Shutemov