From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id 7E7296B002C for ; Wed, 7 Mar 2012 17:01:03 -0500 (EST) Date: Wed, 7 Mar 2012 14:01:01 -0800 From: Andrew Morton Subject: Re: [PATCH 2/5] hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown Message-Id: <20120307140101.b0624e80.akpm@linux-foundation.org> In-Reply-To: <4F101935.1040108@linux.vnet.ibm.com> References: <4F101904.8090405@linux.vnet.ibm.com> <4F101935.1040108@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Xiao Guangrong Cc: William Irwin , linux-mm@kvack.org, LKML On Fri, 13 Jan 2012 19:44:53 +0800 Xiao Guangrong wrote: > Afte call find_vma_prev(mm, addr, &prev_vma), following condition is always > true: > !prev_vma || (addr >= prev_vma->vm_end) > it can be happily drop prev_vma and use find_vma instead of find_vma_prev I had to rework this patch due to 097d59106a8e4b ("vm: avoid using find_vma_prev() unnecessarily") in mainline. Can you please check my handiwork? From: Xiao Guangrong Subject: hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown() After the call find_vma_prev(mm, addr, &prev_vma), the following condition is always true: !prev_vma || (addr >= prev_vma->vm_end) it can happily drop prev_vma and use find_vma() instead of find_vma_prev(). Signed-off-by: Xiao Guangrong Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Michal Hocko Cc: Hillf Danton Cc: Andrea Arcangeli Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton --- arch/x86/mm/hugetlbpage.c | 23 +++++++---------------- 1 file changed, 7 insertions(+), 16 deletions(-) diff -puN arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown arch/x86/mm/hugetlbpage.c --- a/arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown +++ a/arch/x86/mm/hugetlbpage.c @@ -308,7 +308,7 @@ static unsigned long hugetlb_get_unmappe { struct hstate *h = hstate_file(file); struct mm_struct *mm = current->mm; - struct vm_area_struct *vma, *prev_vma; + struct vm_area_struct *vma; unsigned long base = mm->mmap_base, addr = addr0; unsigned long largest_hole = mm->cached_hole_size; int first_time = 1; @@ -334,25 +334,16 @@ try_again: * i.e. return with success: */ vma = find_vma(mm, addr); - if (!vma) - return addr; - - /* - * new region fits between prev_vma->vm_end and - * vma->vm_start, use it: - */ - prev_vma = vma->vm_prev; - if (addr + len <= vma->vm_start && - (!prev_vma || (addr >= prev_vma->vm_end))) { + if (vma) + prev_vma = vma->vm_prev; + if (!vma || addr + len <= vma->vm_start) { /* remember the address as a hint for next time */ mm->cached_hole_size = largest_hole; return (mm->free_area_cache = addr); - } else { + } else if (mm->free_area_cache == vma->vm_end) { /* pull free_area_cache down to the first hole */ - if (mm->free_area_cache == vma->vm_end) { - mm->free_area_cache = vma->vm_start; - mm->cached_hole_size = largest_hole; - } + mm->free_area_cache = vma->vm_start; + mm->cached_hole_size = largest_hole; } /* remember the largest hole we saw so far */ _ -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org