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SubjectRe: [PATCH 1/3] vmalloc: ignore vmalloc area holes in vwrite()
On Tue, 15 Sep 2009 10:18:52 +0800
Wu Fengguang <fengguang.wu@intel.com> wrote:

> Siliently ignore all vmalloc area holes in vwrite(),
> and report success to the caller even if nothing is written.
>
> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

Why don't you modify vread() at the same time ?
Because /proc/kcore ignores return value of vread(), I think you can
modify it without no side-effect.

Regards,
-Kame

> ---
> mm/vmalloc.c | 13 ++-----------
> 1 file changed, 2 insertions(+), 11 deletions(-)
>
> --- linux-mm.orig/mm/vmalloc.c 2009-09-15 10:08:33.000000000 +0800
> +++ linux-mm/mm/vmalloc.c 2009-09-15 10:14:18.000000000 +0800
> @@ -1805,10 +1805,8 @@ finished:
> * @addr: vm address.
> * @count: number of bytes to be read.
> *
> - * Returns # of bytes which addr and buf should be incresed.
> + * Returns # of bytes which addr and buf should be increased.
> * (same number to @count).
> - * If [addr...addr+count) doesn't includes any intersect with valid
> - * vmalloc area, returns 0.
> *
> * This function checks that addr is a valid vmalloc'ed area, and
> * copy data from a buffer to the given addr. If specified range of
> @@ -1816,8 +1814,6 @@ finished:
> * proper area of @buf. If there are memory holes, no copy to hole.
> * IOREMAP area is treated as memory hole and no copy is done.
> *
> - * If [addr...addr+count) doesn't includes any intersects with alive
> - * vm_struct area, returns 0.
> * @buf should be kernel's buffer. Because this function uses KM_USER0,
> * the caller should guarantee KM_USER0 is not used.
> *
> @@ -1834,7 +1830,6 @@ long vwrite(char *buf, char *addr, unsig
> struct vm_struct *tmp;
> char *vaddr;
> unsigned long n, buflen;
> - int copied = 0;
>
> /* Don't allow overflow */
> if ((unsigned long) addr + count < count)
> @@ -1856,18 +1851,14 @@ long vwrite(char *buf, char *addr, unsig
> n = vaddr + tmp->size - PAGE_SIZE - addr;
> if (n > count)
> n = count;
> - if (!(tmp->flags & VM_IOREMAP)) {
> + if (!(tmp->flags & VM_IOREMAP))
> aligned_vwrite(buf, addr, n);
> - copied++;
> - }
> buf += n;
> addr += n;
> count -= n;
> }
> finished:
> read_unlock(&vmlist_lock);
> - if (!copied)
> - return 0;
> return buflen;
> }
>
>
> --
>
>



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