Messages in this thread | | | Date | Tue, 15 Sep 2009 13:21:51 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH 1/3] vmalloc: ignore vmalloc area holes in vwrite() |
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On Tue, Sep 15, 2009 at 11:18:29AM +0800, KAMEZAWA Hiroyuki wrote: > On Tue, 15 Sep 2009 11:15:07 +0800 > Wu Fengguang <fengguang.wu@intel.com> wrote: > > > 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? > > > Okay. I'll write patches for vread/vwrite. And make them just return bool.
bool may not be sufficient? For obviously you need to return -EFAULT for invalid address and I need to return -EIO for hwpoison pages. (I assume you put is_vmalloc_or_module_addr() immediately before the vmalloc_to_page() calls in vmalloc.c, which seems a more natural place than in mem.c.)
Thanks, Fengguang
> true .....requested area includes valid memory range and worth to be copied. > false.....no valid range found. > > Thanks, > -Kame > > > > > > 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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