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From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>,
	David Rientjes <rientjes@google.com>,
	Larry Finger <Larry.Finger@lwfinger.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org
Subject: Re: Sleeping BUG in khugepaged for i586
Date: Fri, 9 Jun 2017 09:43:48 +0200	[thread overview]
Message-ID: <20170609074348.GB21764@dhcp22.suse.cz> (raw)
In-Reply-To: <d348054d-3857-65bb-e896-c4bd2ea6ee85@suse.cz>

On Fri 09-06-17 08:48:58, Vlastimil Babka wrote:
> On 06/08/2017 10:30 PM, Michal Hocko wrote:
> > But I guess you are primary after syncing the preemptive mode for 64 and
> > 32b systems, right? I agree that having a different model is more than
> > unfortunate because 32b gets much less testing coverage and so a risk of
> > introducing a new bug is just a matter of time. Maybe we should make
> > pte_offset_map disable preemption and currently noop pte_unmap to
> > preempt_enable. The overhead should be pretty marginal on x86_64 but not
> > all arches have per-cpu preempt count. So I am not sure we really want
> > to add this to just for the debugging purposes...
> 
> I think adding that overhead for everyone would be unfortunate. It would
> be acceptable, if it was done only for the config option that enables
> the might_sleep() checks (CONFIG_DEBUG_ATOMIC_SLEEP?)

That is certainly possible. But is it worth it?
arch/alpha/include/asm/pgtable.h:#define pte_offset_map(dir,addr)	pte_offset_kernel((dir),(addr))
arch/arc/include/asm/pgtable.h:#define pte_offset_map(dir, addr)		pte_offset(dir, addr)
arch/arm/include/asm/pgtable.h:#define pte_offset_map(pmd,addr)	(__pte_map(pmd) + pte_index(addr))
arch/arm64/include/asm/pgtable.h:#define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
arch/arm64/include/asm/pgtable.h:#define pte_offset_map_nested(dir,addr)	pte_offset_kernel((dir), (addr))
arch/cris/include/asm/pgtable.h:#define pte_offset_map(dir, address) \
arch/frv/include/asm/pgtable.h:#define pte_offset_map(dir, address) \
arch/frv/include/asm/pgtable.h:#define pte_offset_map(dir, address) \
arch/hexagon/include/asm/pgtable.h:#define pte_offset_map(dir, address)                                    \
arch/hexagon/include/asm/pgtable.h:#define pte_offset_map_nested(pmd, addr) pte_offset_map(pmd, addr)
arch/ia64/include/asm/pgtable.h:#define pte_offset_map(dir,addr)	pte_offset_kernel(dir, addr)
arch/m32r/include/asm/pgtable.h:#define pte_offset_map(dir, address)	\
arch/m68k/include/asm/mcf_pgtable.h:#define pte_offset_map(pmdp, addr) ((pte_t *)__pmd_page(*pmdp) + \
arch/m68k/include/asm/motorola_pgtable.h:#define pte_offset_map(pmdp,address) ((pte_t *)__pmd_page(*pmdp) + (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
arch/m68k/include/asm/sun3_pgtable.h:#define pte_offset_map(pmd, address) ((pte_t *)page_address(pmd_page(*pmd)) + pte_index(address))
arch/metag/include/asm/pgtable.h:#define pte_offset_map(dir, address)		pte_offset_kernel(dir, address)
arch/metag/include/asm/pgtable.h:#define pte_offset_map_nested(dir, address)	pte_offset_kernel(dir, address)
arch/microblaze/include/asm/pgtable.h:#define pte_offset_map(dir, addr)		\
arch/mips/include/asm/pgtable-32.h:#define pte_offset_map(dir, address)					\
arch/mips/include/asm/pgtable-64.h:#define pte_offset_map(dir, address)					\
arch/mn10300/include/asm/pgtable.h:#define pte_offset_map(dir, address) \
arch/nios2/include/asm/pgtable.h:#define pte_offset_map(dir, addr)			\
arch/openrisc/include/asm/pgtable.h:#define pte_offset_map(dir, address)	        \
arch/openrisc/include/asm/pgtable.h:#define pte_offset_map_nested(dir, address)     \
arch/parisc/include/asm/pgtable.h:#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
arch/powerpc/include/asm/book3s/32/pgtable.h:#define pte_offset_map(dir, addr)		\
arch/powerpc/include/asm/book3s/64/pgtable.h:#define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
arch/powerpc/include/asm/nohash/32/pgtable.h:#define pte_offset_map(dir, addr)		\
arch/powerpc/include/asm/nohash/64/pgtable.h:#define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
arch/s390/include/asm/pgtable.h:#define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address)
arch/score/include/asm/pgtable.h:#define pte_offset_map(dir, address)	\
arch/sh/include/asm/pgtable_32.h:#define pte_offset_map(dir, address)		pte_offset_kernel(dir, address)
arch/sh/include/asm/pgtable_64.h:#define pte_offset_map(dir,addr)	pte_offset_kernel(dir, addr)
arch/sparc/include/asm/pgtable_32.h:#define pte_offset_map(d, a)		pte_offset_kernel(d,a)
arch/sparc/include/asm/pgtable_64.h:#define pte_offset_map			pte_index
arch/tile/include/asm/pgtable.h:#define pte_offset_map(dir, address) pte_offset_kernel(dir, address)
arch/um/include/asm/pgtable.h:#define pte_offset_map(dir, address) \
arch/unicore32/include/asm/pgtable.h:#define pte_offset_map(dir, addr)	(pmd_page_vaddr(*(dir)) \
arch/x86/include/asm/pgtable_32.h:#define pte_offset_map(dir, address)					\
arch/x86/include/asm/pgtable_32.h:#define pte_offset_map(dir, address)					\
arch/x86/include/asm/pgtable_64.h:#define pte_offset_map(dir, address) pte_offset_kernel((dir), (address))
arch/xtensa/include/asm/pgtable.h:#define pte_offset_map(dir,addr)	pte_offset_kernel((dir),(addr))
include/linux/mm.h:#define pte_offset_map_lock(mm, pmd, address, ptlp)	\
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2017-06-09  7:43 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-03 19:24 Sleeping BUG in khugepaged for i586 Larry Finger
2017-06-05 21:44 ` Andrew Morton
2017-06-06 14:02   ` Vlastimil Babka
2017-06-06 15:01     ` Larry Finger
2017-06-07  7:19       ` Vlastimil Babka
2017-06-07 20:56         ` David Rientjes
2017-06-08 14:48           ` Michal Hocko
2017-06-08 17:05             ` Matthew Wilcox
2017-06-08 20:18               ` Michal Hocko
2017-06-08 20:30                 ` Michal Hocko
2017-06-09  6:48                   ` Vlastimil Babka
2017-06-09  7:43                     ` Michal Hocko [this message]
2017-06-09 14:28                     ` Larry Finger
2017-06-09 22:38                   ` David Rientjes
2017-06-10  8:09                     ` Michal Hocko
2017-06-11 23:28                       ` David Rientjes
2017-06-12  6:29                         ` Michal Hocko
2017-06-15  0:28                           ` David Rientjes
2017-06-15  1:12             ` David Rientjes
2017-06-15  8:32               ` Michal Hocko
2017-06-23 12:08             ` Michal Hocko
2017-06-23 13:13               ` Vlastimil Babka
2017-06-23 13:25                 ` Michal Hocko
2017-06-23 15:28                   ` Larry Finger
2017-06-08 15:29           ` Larry Finger

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