Messages in this thread | | | Date | Thu, 17 Sep 2009 14:02:39 +0800 | Subject | Re: [PATCH 2/3][mmotm] showing size of kcore | From | Américo Wang <> |
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On Thu, Sep 17, 2009 at 10:44 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > Now, size of /proc/kcore which can be read by 'ls -l' is 0. > But it's not correct value. > > This is a patch for showing size of /proc/kcore as following. > > On x86-64, ls -l shows > ... root root 140737486266368 2009-09-17 10:29 /proc/kcore > Then, 7FFFFFFE02000. This comes from vmalloc area's size. > (*) This shows "core" size, not memory size. > > This patch shows the size by updating "size" field in struct proc_dir_entry. > Later, lookup routine will create inode and fill inode->i_size based > on this value. Then, this has a problem. > > - Once inode is cached, inode->i_size will never be updated. > > Then, this patch is not memory-hotplug-aware. > > To update inode->i_size, we have to know dentry or inode. > But there is no way to lookup them by inside kernel. Hmmm.... > Next patch will try it. > > Cc: WANG Cong <xiyou.wangcong@gmail.com> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > --- > fs/proc/kcore.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > Index: mmotm-2.6.31-Sep14/fs/proc/kcore.c > =================================================================== > --- mmotm-2.6.31-Sep14.orig/fs/proc/kcore.c > +++ mmotm-2.6.31-Sep14/fs/proc/kcore.c > @@ -107,6 +107,8 @@ static void free_kclist_ents(struct list > */ > static void __kcore_update_ram(struct list_head *list) > { > + int nphdr; > + size_t size; > struct kcore_list *tmp, *pos; > LIST_HEAD(garbage); > > @@ -124,6 +126,7 @@ static void __kcore_update_ram(struct li > write_unlock(&kclist_lock); > > free_kclist_ents(&garbage); > + proc_root_kcore->size = get_kcore_size(&nphdr, &size);
This makes me to think if we will have some race condition here? Two processes can open kcore at the same time...
> } > > > @@ -429,7 +432,8 @@ read_kcore(struct file *file, char __use > unsigned long start; > > read_lock(&kclist_lock); > - proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen); > + size = get_kcore_size(&nphdr, &elf_buflen); > + > if (buflen == 0 || *fpos >= size) { > read_unlock(&kclist_lock); > return 0; > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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