[RFC v2] arm:extend the reserved mrmory for initrd to be page aligned
From: Russell King - ARM Linux <hidden>
Date: 2014-09-15 11:33:35
Also in:
linux-arm-msm, linux-mm, lkml
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:
quoted hunk ↗ jump to hunk
Signed-off-by: Yalin Wang <redacted> --- 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:
quoted hunk ↗ jump to hunk
@@ -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.