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SubjectRe: [PATCH 1/3] vmalloc: ignore vmalloc area holes in vwrite()
Hi Kame,

I'll go out for a while. If you are going to do your improvements to
vmalloc.c, please feel free to do so. I can rebase the hwpoison bits
after yours.

I could do the kmem part(in a modified patch 2/3) and let it return
any error code vread/vwrite reports. Ideally the kmem read/write
could do

if (zero bytes successfully read/written)
return error_code;
else
return bytes_so_far;
Do you agree?

Thanks,
Fengguang

On Tue, Sep 15, 2009 at 10:34:25AM +0800, KAMEZAWA Hiroyuki wrote:
> 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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