From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx118.postini.com [74.125.245.118]) by kanga.kvack.org (Postfix) with SMTP id C8D746B0002 for ; Tue, 19 Feb 2013 13:08:59 -0500 (EST) Received: by mail-da0-f53.google.com with SMTP id w3so3072108dad.40 for ; Tue, 19 Feb 2013 10:08:59 -0800 (PST) Date: Tue, 19 Feb 2013 10:08:12 -0800 (PST) From: Hugh Dickins Subject: Re: [PATCH 1/2] mm: Allow arch code to control the user page table ceiling In-Reply-To: <1361204311-14127-2-git-send-email-catalin.marinas@arm.com> Message-ID: References: <1361204311-14127-1-git-send-email-catalin.marinas@arm.com> <1361204311-14127-2-git-send-email-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas Cc: Andrew Morton , Russell King - ARM Linux , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org On Mon, 18 Feb 2013, Catalin Marinas wrote: > From: Hugh Dickins You're being generous to me :) Thanks for doing most of the work, yes, this looks fine. BUt I'd have expected a Cc stable below: see comment on 2/2. Hugh > > On architectures where a pgd entry may be shared between user and kernel > (ARM+LPAE), freeing page tables needs a ceiling other than 0. This patch > introduces a generic USER_PGTABLES_CEILING that arch code can override. > > Signed-off-by: Hugh Dickins > [catalin.marinas@arm.com: commit log; shift_arg_pages(), asm-generic/pgtables.h changes] > Signed-off-by: Catalin Marinas > Cc: Russell King > Cc: Andrew Morton > --- > fs/exec.c | 4 ++-- > include/asm-generic/pgtable.h | 10 ++++++++++ > mm/mmap.c | 4 ++-- > 3 files changed, 14 insertions(+), 4 deletions(-) > > diff --git a/fs/exec.c b/fs/exec.c > index 20df02c..547eaaa 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -613,7 +613,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) > * when the old and new regions overlap clear from new_end. > */ > free_pgd_range(&tlb, new_end, old_end, new_end, > - vma->vm_next ? vma->vm_next->vm_start : 0); > + vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); > } else { > /* > * otherwise, clean from old_start; this is done to not touch > @@ -622,7 +622,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) > * for the others its just a little faster. > */ > free_pgd_range(&tlb, old_start, old_end, new_end, > - vma->vm_next ? vma->vm_next->vm_start : 0); > + vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING); > } > tlb_finish_mmu(&tlb, new_end, old_end); > > diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h > index 5cf680a..f50a87d 100644 > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -7,6 +7,16 @@ > #include > #include > > +/* > + * On almost all architectures and configurations, 0 can be used as the > + * upper ceiling to free_pgtables(): on many architectures it has the same > + * effect as using TASK_SIZE. However, there is one configuration which > + * must impose a more careful limit, to avoid freeing kernel pgtables. > + */ > +#ifndef USER_PGTABLES_CEILING > +#define USER_PGTABLES_CEILING 0UL > +#endif > + > #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS > extern int ptep_set_access_flags(struct vm_area_struct *vma, > unsigned long address, pte_t *ptep, > diff --git a/mm/mmap.c b/mm/mmap.c > index d1e4124..e262710 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -2262,7 +2262,7 @@ static void unmap_region(struct mm_struct *mm, > update_hiwater_rss(mm); > unmap_vmas(&tlb, vma, start, end); > free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, > - next ? next->vm_start : 0); > + next ? next->vm_start : USER_PGTABLES_CEILING); > tlb_finish_mmu(&tlb, start, end); > } > > @@ -2640,7 +2640,7 @@ void exit_mmap(struct mm_struct *mm) > /* Use -1 here to ensure all VMAs in the mm are unmapped */ > unmap_vmas(&tlb, vma, 0, -1); > > - free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); > + free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); > tlb_finish_mmu(&tlb, 0, -1); > > /* > -- 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