Re: Regression in v4.0.0-rc1 with Android Binder

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Feb 27, 2015 at 03:34:32AM +0530, Amit Pundir wrote:
> Hi,
> 
> I ran into series of following binder mmap failures with v4.0.0-rc1:
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1971 at mm/vmalloc.c:130
> vmap_page_range_noflush+0x119/0x144()
> CPU: 0 PID: 1971 Comm: healthd Not tainted 4.0.0-rc1-00399-g7da3fdc-dirty #157
> Hardware name: ARM-Versatile Express
> [<c001246d>] (unwind_backtrace) from [<c000f7f9>] (show_stack+0x11/0x14)
> [<c000f7f9>] (show_stack) from [<c049a221>] (dump_stack+0x59/0x7c)
> [<c049a221>] (dump_stack) from [<c001cf21>] (warn_slowpath_common+0x55/0x84)
> [<c001cf21>] (warn_slowpath_common) from [<c001cfe3>]
> (warn_slowpath_null+0x17/0x1c)
> [<c001cfe3>] (warn_slowpath_null) from [<c00c66c5>]
> (vmap_page_range_noflush+0x119/0x144)
> [<c00c66c5>] (vmap_page_range_noflush) from [<c00c716b>] (map_vm_area+0x27/0x48)
> [<c00c716b>] (map_vm_area) from [<c038ddaf>]
> (binder_update_page_range+0x12f/0x27c)
> [<c038ddaf>] (binder_update_page_range) from [<c038e857>]
> (binder_mmap+0xbf/0x1ac)
> [<c038e857>] (binder_mmap) from [<c00c2dc7>] (mmap_region+0x2eb/0x4d4)
> [<c00c2dc7>] (mmap_region) from [<c00c3197>] (do_mmap_pgoff+0x1e7/0x250)
> [<c00c3197>] (do_mmap_pgoff) from [<c00b35b5>] (vm_mmap_pgoff+0x45/0x60)
> [<c00b35b5>] (vm_mmap_pgoff) from [<c00c1f39>] (SyS_mmap_pgoff+0x5d/0x80)
> [<c00c1f39>] (SyS_mmap_pgoff) from [<c000ce81>] (ret_fast_syscall+0x1/0x5c)
> ---[ end trace 48c2c4b9a1349e54 ]---
> binder: 1982: binder_alloc_buf failed to map page at f0e00000 in kernel
> binder: binder_mmap: 1982 b6bde000-b6cdc000 alloc small buf failed -12
> 
> 
> Turned out that the following commit tripped off binder:
> ----------8<----------
> commit 71394fe50146202f2c8d92cf50f5ebc761acf254
> Author: Andrey Ryabinin <a.ryabinin@samsung.com>
> Date:   Fri Feb 13 14:40:03 2015 -0800
> 
>     mm: vmalloc: add flag preventing guard hole allocation
> ---------->8----------
> 
> 
> Explicitly disabling the vmalloc no guard (VM_NO_GUARD) flag in binder
> worked fine for me. So does a fix like this look reasonable enough to
> submit?
> ----------8<----------
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -601,6 +601,7 @@ static int binder_update_page_range(struct
> binder_proc *proc, int allocate,
>                         goto err_alloc_page_failed;
>                 }
>                 tmp_area.addr = page_addr;
> +               tmp_area.flags &= ~VM_NO_GUARD;
>                 tmp_area.size = PAGE_SIZE + PAGE_SIZE /* guard page? */;
>                 ret = map_vm_area(&tmp_area, PAGE_KERNEL, page);
>                 if (ret) {
> ---------->8----------

This looks like a valid fix, please send it in.

thanks,

greg k-h