Messages in this thread Patch in this message | | | Date | Tue, 27 Aug 2013 14:34:15 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2 3/3] mm/hwpoison: fix return value of madvise_hwpoison |
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On Tue, 27 Aug 2013 16:02:29 +0800 Wanpeng Li <liwanp@linux.vnet.ibm.com> wrote:
> Hi Chen, > On Tue, Aug 27, 2013 at 03:37:01AM -0400, Chen Gong wrote: > >> On Tue, Aug 27, 2013 at 11:38:27AM +0800, Wanpeng Li wrote: > >> > Hi Naoya, > >> > On Mon, Aug 26, 2013 at 11:28:16PM -0400, Naoya Horiguchi wrote: > >> > >On Tue, Aug 27, 2013 at 10:39:31AM +0800, Wanpeng Li wrote: > >> > >> The return value outside for loop is always zero which means madvise_hwpoison > >> > >> return success, however, this is not truth for soft_offline_page w/ failure > >> > >> return value. > >> > > > >> > >I don't understand what you want to do for what reason. Could you clarify > >> > >those? > >> > > >> > int ret is defined in two place in madvise_hwpoison. One is out of for > >> > loop and its value is always zero(zero means success for madvise), the > >> > other one is in for loop. The soft_offline_page function maybe return > >> > -EBUSY and break, however, the ret out of for loop is return which means > >> > madvise_hwpoison success. > >> > >> Oh, I see. Thanks. > >> > >I don't think such change is a good idea. The original code is obviously > >easy to confuse people. Why not removing redundant local variable? > > > > I think the trick here is get_user_pages_fast will return the number of > pages pinned. It is always 1 in madvise_hwpoison, the return value of > memory_failure is ignored. Therefore we still need to reset ret to 0 > before return madvise_hwpoison.
erk, madvise_hwpoison() has two locals with the same name. Bad.
From: Andrew Morton <akpm@linux-foundation.org> Subject: mm/madvise.c:madvise_hwpoison(): remove local `ret'
madvise_hwpoison() has two locals called "ret". Fix it all up.
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
mm/madvise.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff -puN mm/madvise.c~a mm/madvise.c --- a/mm/madvise.c~a +++ a/mm/madvise.c @@ -343,15 +343,16 @@ static long madvise_remove(struct vm_are */ static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end) { - int ret = 0; - if (!capable(CAP_SYS_ADMIN)) return -EPERM; for (; start < end; start += PAGE_SIZE) { struct page *p; - int ret = get_user_pages_fast(start, 1, 0, &p); + int ret; + + ret = get_user_pages_fast(start, 1, 0, &p); if (ret != 1) return ret; + if (PageHWPoison(p)) { put_page(p); continue; @@ -369,7 +370,7 @@ static int madvise_hwpoison(int bhv, uns /* Ignore return value for now */ memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED); } - return ret; + return 0; } #endif _
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