Re: [PATCH] mm/gup: check page posion status for coredump.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, 18 Mar 2021 04:46:00 +0000
Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:

> On Wed, Mar 17, 2021 at 10:12:02AM +0100, David Hildenbrand wrote:
> > > +	if (IS_ENABLED(CONFIG_MEMORY_FAILURE) && ret == 1) {
> > > +		if (unlikely(PageHuge(page) && PageHWPoison(compound_head(page))))
> > > +			ret = 0;
> > > +		else if (unlikely(PageHWPoison(page)))
> > > +			ret = 0;
> > > +	}  
> > 
> > I wonder if a simple
> > 
> > if (PageHWPoison(compound_head(page)))
> > 	ret = 0;
> > 
> > won't suffice. But I guess the "issue" is compound pages that are not huge
> > pages or transparent huge pages.  
> 
> THPs don't set the HWPoison bit on the head page.
> 
> https://lore.kernel.org/linux-mm/20210316140947.GA3420@xxxxxxxxxxxxxxxxxxxx/
> 
> (and PAGEFLAG(HWPoison, hwpoison, PF_ANY))
> 
> By the way,
> 
> #ifdef CONFIG_MEMORY_FAILURE
> PAGEFLAG(HWPoison, hwpoison, PF_ANY)
> TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
> #define __PG_HWPOISON (1UL << PG_hwpoison)
> extern bool take_page_off_buddy(struct page *page);
> #else
> PAGEFLAG_FALSE(HWPoison)
> #define __PG_HWPOISON 0
> #endif
> 
> so there's no need for this 
> 	if (IS_ENABLED(CONFIG_MEMORY_FAILURE)
> check, as it simply turns into
> 
> 	if (PageHuge(page) && 0)
> 	else if (0)
> 
> and the compiler can optimise it all away.

Yes, You are right, I will modify this later.
Thanks for correction

-- 
Thanks!
Aili Yao




[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux