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Re: [Qemu-devel] [PATCH] linux-user: Fixed brk syscall memory allocation
From: |
Stanislav Shmarov |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: Fixed brk syscall memory allocation |
Date: |
Wed, 14 Sep 2016 15:01:24 +0300 |
Please ignore this patch. Issue was in another place, and proposed solution
is simply wrong.
2016-09-13 16:14 GMT+03:00 Stanislav Shmarov <address@hidden>:
> When application is trying to allocate memory through brk
> QEMU is allocating host memory using mmap.
> Without MAP_FIXED attribute it is possible that memory will
> never be allocated in desired place, and brk syscall will
> act like there is no avalible memory.
>
> Signed-off-by: Stanislav Shmarov <address@hidden>
> ---
> linux-user/syscall.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index ca06943..2861db2 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1030,7 +1030,8 @@ abi_long do_brk(abi_ulong new_brk)
> new_alloc_size = HOST_PAGE_ALIGN(new_brk - brk_page);
> mapped_addr = get_errno(target_mmap(brk_page, new_alloc_size,
> PROT_READ|PROT_WRITE,
> - MAP_ANON|MAP_PRIVATE, 0, 0));
> + MAP_ANON | MAP_PRIVATE |
> MAP_FIXED,
> + 0, 0));
>
> if (mapped_addr == brk_page) {
> /* Heap contents are initialized to zero, as for anonymous
> --
> 1.9.3
>
>