On Thu, 23 Jan 2014 20:27:29 +0400 (MSK) malc <[email protected]> wrote:
> Sep 17 00:00:00 2001 > From: Vladimir Murzin <[email protected]> > Date: Thu, 23 Jan 2014 14:54:20 +0400 > Subject: [PATCH] Revert "mm/vmalloc: interchage the implementation of > vmalloc_to_{pfn,page}" > > This reverts commit ece86e222db48d04bda218a2be70e384518bb08c. > > Despite being claimed that patch doesn't introduce any functional > changes in fact it does. > > The "no page" path behaves different now. Originally, vmalloc_to_page > might return NULL under some conditions, with new implementation it returns > pfn_to_page(0) which is not the same as NULL. > > Simple test shows the difference. > > test.c > > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/vmalloc.h> > #include <linux/mm.h> > > int __init myi(void) > { > struct page *p; > void *v; > > v = vmalloc(PAGE_SIZE); > /* trigger the "no page" path in vmalloc_to_page*/ > vfree(v); > > p = vmalloc_to_page(v); > > pr_err("expected val = NULL, returned val = %p", p); > > return -EBUSY; > } > > void __exit mye(void) > { > > } > module_init(myi) > module_exit(mye) > > Before interchange: > expected val = NULL, returned val = (null) > > After interchange: > expected val = NULL, returned val = c7ebe000 > hm, yes, I suppose that's bad. Rather than reverting the patch we could fix up vmalloc_to_pfn() and/or vmalloc_to_page() to handle this situation. Did you try that? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
