On Fri, Dec 07, 2012 at 10:16:55PM +0900, JoonSoo Kim wrote: > 2012/12/7 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>: > > On Fri, 7 Dec 2012 01:09:27 +0900 > > Joonsoo Kim <js1304@xxxxxxxxx> wrote: > > > >> I'm not sure that "7/8: makes vmlist only for kexec" is fine. > >> Because it is related to userspace program. > >> As far as I know, makedumpfile use kexec's output information and it only > >> need first address of vmalloc layer. So my implementation reflect this > >> fact, but I'm not sure. And now, I don't fully test this patchset. > >> Basic operation work well, but I don't test kexec. So I send this > >> patchset with 'RFC'. > > > > Yes, this is irritating. Perhaps Vivek or one of the other kexec > > people could take a look at this please - if would obviously be much > > better if we can avoid merging [patch 7/8] at all. > > I'm not sure, but I almost sure that [patch 7/8] have no problem. > In kexec.c, they write an address of vmlist and offset of vm_struct's > address field. > It imply that user for this information doesn't have any other > information about vm_struct, > and they can't use other field of vm_struct. They can use *only* address field. > So, remaining just one vm_struct for vmlist which represent first area > of vmalloc layer > may be safe. I browsed through makedumpfile source quickly. So yes it does look like that we look at first vmlist element ->addr field to figure out where vmalloc area is starting. Can we get the same information from this rb-tree of vmap_area? Is ->va_start field communication same information as vmlist was communicating? What's the difference between vmap_area_root and vmlist. So without knowing details of both the data structures, I think if vmlist is going away, then user space tools should be able to traverse vmap_area_root rb tree. I am assuming it is sorted using ->addr field and we should be able to get vmalloc area start from there. It will just be a matter of exporting right fields to user space (instead of vmlist). CCing Atsushi Kumagai and Dave Anderson. Atsushi-san is the one who maintains makedumpfile. Dave Anderson maintains "crash" and looks like it already has the capability to traverse through vmap_area_root rb-tree. So please let us know if left most element of vmap_area_root rb-tree will give us start of vmalloc area or not? Thanks Vivek -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>