Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread h...@lst.de
On Tue, Apr 20, 2021 at 11:20:19PM +0200, Arnd Bergmann wrote: > In that case, there should be no problem for you. > > The main issue is with system calls and ioctls that contain a misaligned > struct member like > > struct s { >u32 a; >u64 b; > }; > > Passing this structure by r

Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread Vineet Gupta
On 4/20/21 12:07 AM, Arnd Bergmann wrote: > On Tue, Apr 20, 2021 at 5:10 AM Matthew Wilcox wrote: >> On Tue, Apr 20, 2021 at 02:48:17AM +, Vineet Gupta wrote: 32-bit architectures which expect 8-byte alignment for 8-byte integers and need 64-bit DMA addresses (arc, arm, mips, ppc) ha

Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread Arnd Bergmann
On Tue, Apr 20, 2021 at 11:14 PM Vineet Gupta wrote: > On 4/20/21 12:07 AM, Arnd Bergmann wrote: > > > > which means that half the 32-bit architectures do this. This may > > cause more problems when arc and/or microblaze want to support > > 64-bit kernels and compat mode in the future on their la

Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread Matthew Wilcox
On Tue, Apr 20, 2021 at 09:39:54AM +0200, Geert Uytterhoeven wrote: > > +++ b/include/linux/mm_types.h > > @@ -97,10 +97,10 @@ struct page { > > }; > > struct {/* page_pool used by netstack */ > > /** > > -* @dm

RE: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread David Laight
From: Geert Uytterhoeven > Sent: 20 April 2021 08:40 > > Hi Willy, > > On Sat, Apr 17, 2021 at 4:49 AM Matthew Wilcox wrote: > > Replacement patch to fix compiler warning. > > > > 32-bit architectures which expect 8-byte alignment for 8-byte integers > > and need 64-bit DMA addresses (arc, arm,

Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread Geert Uytterhoeven
Hi Willy, On Sat, Apr 17, 2021 at 4:49 AM Matthew Wilcox wrote: > Replacement patch to fix compiler warning. > > From: "Matthew Wilcox (Oracle)" > Date: Fri, 16 Apr 2021 16:34:55 -0400 > Subject: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems > To: bro...@redhat.com > Cc: linux-ker...@

Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread Rasmus Villemoes
On 17/04/2021 01.07, Matthew Wilcox (Oracle) wrote: > 32-bit architectures which expect 8-byte alignment for 8-byte integers > and need 64-bit DMA addresses (arc, arm, mips, ppc) had their struct > page inadvertently expanded in 2019. When the dma_addr_t was added, > it forced the alignment of the

Re: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems

2021-04-20 Thread Arnd Bergmann
On Tue, Apr 20, 2021 at 5:10 AM Matthew Wilcox wrote: > > On Tue, Apr 20, 2021 at 02:48:17AM +, Vineet Gupta wrote: > > > 32-bit architectures which expect 8-byte alignment for 8-byte integers > > > and need 64-bit DMA addresses (arc, arm, mips, ppc) had their struct > > > page inadvertently e