lkml.org 
[lkml]   [2014]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Date
    SubjectRE: [RFC v2] arm:extend the reserved mrmory for initrd to be page aligned
    Great!
    yeah, you are right,
    just keep the change in free_initrd_mem( ) is ok.
    we don't need keep reserved memory to be aligned ,

    Thanks!

    ________________________________________
    From: Russell King - ARM Linux [linux@arm.linux.org.uk]
    Sent: Monday, September 15, 2014 7:33 PM
    To: Wang, Yalin
    Cc: 'Will Deacon'; 'linux-kernel@vger.kernel.org'; 'linux-arm-kernel@lists.infradead.org'; 'linux-mm@kvack.org'; 'linux-arm-msm@vger.kernel.org'
    Subject: Re: [RFC v2] arm:extend the reserved mrmory for initrd to be page aligned

    On Mon, Sep 15, 2014 at 07:07:20PM +0800, Wang, Yalin wrote:
    > this patch extend the start and end address of initrd to be page aligned,
    > so that we can free all memory including the un-page aligned head or tail
    > page of initrd, if the start or end address of initrd are not page
    > aligned, the page can't be freed by free_initrd_mem() function.

    Better, but I think it's more complicated than it needs to be:

    > Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
    > ---
    > arch/arm/mm/init.c | 19 +++++++++++++++++--
    > arch/arm64/mm/init.c | 37 +++++++++++++++++++++++++++++++++----
    > 2 files changed, 50 insertions(+), 6 deletions(-)
    >
    > diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
    > index 659c75d..8490b70 100644
    > --- a/arch/arm/mm/init.c
    > +++ b/arch/arm/mm/init.c
    > @@ -277,6 +277,8 @@ phys_addr_t __init arm_memblock_steal(phys_addr_t size, phys_addr_t align)
    > void __init arm_memblock_init(const struct machine_desc *mdesc)
    > {
    > /* Register the kernel text, kernel data and initrd with memblock. */
    > + phys_addr_t phys_initrd_start_orig __maybe_unused;
    > + phys_addr_t phys_initrd_size_orig __maybe_unused;
    > #ifdef CONFIG_XIP_KERNEL
    > memblock_reserve(__pa(_sdata), _end - _sdata);
    > #else
    > @@ -289,6 +291,13 @@ void __init arm_memblock_init(const struct machine_desc *mdesc)
    > phys_initrd_size = initrd_end - initrd_start;
    > }
    > initrd_start = initrd_end = 0;
    > + phys_initrd_start_orig = phys_initrd_start;
    > + phys_initrd_size_orig = phys_initrd_size;
    > + /* make sure the start and end address are page aligned */
    > + phys_initrd_size = round_up(phys_initrd_start + phys_initrd_size, PAGE_SIZE);
    > + phys_initrd_start = round_down(phys_initrd_start, PAGE_SIZE);
    > + phys_initrd_size -= phys_initrd_start;
    > +
    > if (phys_initrd_size &&
    > !memblock_is_region_memory(phys_initrd_start, phys_initrd_size)) {
    > pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region - disabling initrd\n",
    > @@ -305,9 +314,10 @@ void __init arm_memblock_init(const struct machine_desc *mdesc)
    > memblock_reserve(phys_initrd_start, phys_initrd_size);
    >
    > /* Now convert initrd to virtual addresses */
    > - initrd_start = __phys_to_virt(phys_initrd_start);
    > - initrd_end = initrd_start + phys_initrd_size;
    > + initrd_start = __phys_to_virt(phys_initrd_start_orig);
    > + initrd_end = initrd_start + phys_initrd_size_orig;
    > }
    > +

    I think all the above is entirely unnecessary. The memblock APIs
    (especially memblock_reserve()) will mark the overlapped pages as reserved
    - they round down the starting address, and round up the end address
    (calculated from start + size).

    Hence, this:

    > @@ -636,6 +646,11 @@ static int keep_initrd;
    > void free_initrd_mem(unsigned long start, unsigned long end)
    > {
    > if (!keep_initrd) {
    > + if (start == initrd_start)
    > + start = round_down(start, PAGE_SIZE);
    > + if (end == initrd_end)
    > + end = round_up(end, PAGE_SIZE);
    > +
    > poison_init_mem((void *)start, PAGE_ALIGN(end) - start);
    > free_reserved_area((void *)start, (void *)end, -1, "initrd");
    > }

    is the only bit of code you likely need to achieve your goal.

    Thinking about this, I think that you are quite right to align these.
    The memory around the initrd is defined to be system memory, and we
    already free the pages around it, so it *is* wrong not to free the
    partial initrd pages.

    Good catch.

    --
    FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
    according to speedtest.net.
    \
     
     \ /
      Last update: 2014-09-15 17:01    [W:2.951 / U:0.856 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site