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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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