Re: [PATCH] arm: flush: check if the folio is reserved for IMO addresses

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Thu, Feb 22, 2024 at 10:06:04PM +0800, Kefeng Wang wrote:
> 
> 
> On 2024/2/22 22:01, Yongqiang Liu wrote:
> > Since commit a4d5613c4dc6 ("arm: extend pfn_valid to take into account
> > freed memory map alignment") changes the semantics of pfn_valid() to check
> > presence of the memory map for a PFN. A valid page for an address which
> > is reserved but not mapped by the kernel[1].In Some uio case we will get
> > a crash on a system with the following memory layout:
> > 
> >   node   0: [mem 0x00000000c0a00000-0x00000000cc8fffff]
> >   node   0: [mem 0x00000000d0000000-0x00000000da1fffff]
> >   the uio layout is：0xc0900000, 0x100000
> > 
> > the crash backtrace like:
> > 
> >    Unable to handle kernel paging request at virtual address bff00000
> >    [...]
> >    CPU: 1 PID: 465 Comm: startapp.bin Tainted: G           O      5.10.0 #1
> >    Hardware name: Generic DT based system
> >    PC is at b15_flush_kern_dcache_area+0x24/0x3c
> >    LR is at __sync_icache_dcache+0x6c/0x98
> >    [...]
> >     (b15_flush_kern_dcache_area) from (__sync_icache_dcache+0x6c/0x98)
> >     (__sync_icache_dcache) from (set_pte_at+0x28/0x54)
> >     (set_pte_at) from (remap_pfn_range+0x1a0/0x274)
> >     (remap_pfn_range) from (uio_mmap+0x184/0x1b8 [uio])
> >     (uio_mmap [uio]) from (__mmap_region+0x264/0x5f4)
> >     (__mmap_region) from (__do_mmap_mm+0x3ec/0x440)
> >     (__do_mmap_mm) from (do_mmap+0x50/0x58)
> >     (do_mmap) from (vm_mmap_pgoff+0xfc/0x188)
> >     (vm_mmap_pgoff) from (ksys_mmap_pgoff+0xac/0xc4)
> >     (ksys_mmap_pgoff) from (ret_fast_syscall+0x0/0x5c)
> >    Code: e0801001 e2423001 e1c00003 f57ff04f (ee070f3e)
> >    ---[ end trace 09cf0734c3805d52 ]---
> >    Kernel panic - not syncing: Fatal exception
> > 
> > So check if PG_reserved was set to solve this issue.
> > 
> > [1]: https://lore.kernel.org/lkml/Zbtdue57RO0QScJM@linux.ibm.com/
> > 
> > Fixes: a4d5613c4dc6 ("arm: extend pfn_valid to take into account freed memory map alignment")
> > Suggested-by: Mike Rapoport <rppt@linux.ibm.com>
> > Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
> > ---
> >   arch/arm/mm/flush.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
> > index d19d140a10c7..f2b99223a0ab 100644
> > --- a/arch/arm/mm/flush.c
> > +++ b/arch/arm/mm/flush.c
> > @@ -15,6 +15,7 @@
> >   #include <asm/smp_plat.h>
> >   #include <asm/tlbflush.h>
> >   #include <linux/hugetlb.h>
> > +#include <linux/memblock.h>
> 这个删掉吧然后发出去

Speak English so that everyone knows what you are saying. You are
participating in an international community where English is the
language that we use to communicate between ourselves.

Thanks.

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