Andrew, David, Any comments on this? On Sun, May 24, 2020 at 07:53:58PM +0300, Mike Rapoport wrote: > From: Mike Rapoport <rppt@xxxxxxxxxxxxx> > > sparc32 never registered the memory occupied by the kernel image with > memblock_add() and it only reserved this memory with meblock_reserve(). > > With openbios as system firmware, the memory occupied by the kernel is > reserved in openbios and removed from mem.available. The prom setup code in > the kernel uses mem.available to set up the memory banks and essentially > there is a hole for the memory occupied by the kernel image. > > Later in bootmem_init() this memory is memblock_reserve()d. > > Up until recently, memmap initialization would call __init_single_page() > for the pages in that hole, the free_low_memory_core_early() would mark > them as reserved and everything would be Ok. > > After the change in memmap initialization introduced by the commit "mm: > memmap_init: iterate over memblock regions rather that check each PFN", the > hole is skipped and the page structs for it are not initialized. And when > they are passed from memblock to page allocator as reserved, the latter > gets confused. > > Simply registering the memory occupied by the kernel with memblock_add() > resolves this issue. > > Tested on qemu-system-sparc with Debian Etch [1] userspace. > > [1] https://people.debian.org/~aurel32/qemu/sparc/debian_etch_sparc_small.qcow2 > > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > Link: https://lkml.kernel.org/r/20200517000050.GA87467@roeck-us.nlllllet/ > --- > > David, > > I'd really appreciate your Ack or an explanation where my analysis is wrong :) > > arch/sparc/mm/init_32.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/sparc/mm/init_32.c b/arch/sparc/mm/init_32.c > index e45160839f79..eb2946b1df8a 100644 > --- a/arch/sparc/mm/init_32.c > +++ b/arch/sparc/mm/init_32.c > @@ -192,6 +192,7 @@ unsigned long __init bootmem_init(unsigned long *pages_avail) > /* Reserve the kernel text/data/bss. */ > size = (start_pfn << PAGE_SHIFT) - phys_base; > memblock_reserve(phys_base, size); > + memblock_add(phys_base, size); > > size = memblock_phys_mem_size() - memblock_reserved_size(); > *pages_avail = (size >> PAGE_SHIFT) - high_pages; > -- > 2.26.2 > -- Sincerely yours, Mike.
