if CONFIG_PAGEALLOC is enabled then X86_FEATURE_PSE is disabled and all
the kernel physical RAM pagetables are set up as 4K pages. This is
needed so that CONFIG_PAGEALLOC can do finegrained mapping and unmapping
of pages.
as a side-effect though, the total size of memory allocated as kernel
pagetables increases significantly. All these pagetables are allocated
via alloc_bootmem_low_pages(), straight out of the lowmem DMA pool. If
the system has enough RAM and a large kernel image then almost all of
the 16 MB lowmem DMA pool is allocated to the image and to pagetables -
leaving no space for __GFP_DMA allocations.
this results in drivers failing and the bootup hanging:
swapper invoked oom-killer: gfp_mask=0x80d1, order=0, oomkilladj=0
[<4015059f>] out_of_memory+0x17f/0x1c0
[<40151f3c>] __alloc_pages+0x37c/0x3a0
[<40168cd7>] slob_new_page+0x37/0x50
[<40168dff>] slob_alloc+0x10f/0x190
[<40169010>] __kmalloc_node+0x80/0x90
[<405a17e3>] scsi_host_alloc+0x33/0x2c0
[<405a1a82>] scsi_register+0x12/0x60
[<40d5889e>] aha1542_detect+0x9e/0x940
[<405c5ba5>] ultrastor_detect+0x265/0x5f0
[<401352f5>] getnstimeofday+0x35/0xf0
[<40d58751>] init_this_scsi_driver+0x41/0xf0
[<40d0b856>] kernel_init+0x136/0x310
[<40d58710>] init_this_scsi_driver+0x0/0xf0
[<40d0b720>] kernel_init+0x0/0x310
[<40105547>] kernel_thread_helper+0x7/0x10
=======================
the fix is to first allocate from above the DMA pool, and if that fails
(for example due to it being a machine with less than 16 MB of RAM),
allocate from the DMA pool as a fallback.
With this fix applied i was able to boot a PAGEALLOC=y kernel that would
hang before.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now, arch dependent code around CONFIG_MEMORY_HOTREMOVE is a mess.
This patch cleans up them. This is against 2.6.23-rc6-mm1.
- fix compile failure on ia64/ CONFIG_MEMORY_HOTPLUG && !CONFIG_MEMORY_HOTREMOVE case.
- For !CONFIG_MEMORY_HOTREMOVE, add generic no-op remove_memory(),
which returns -EINVAL.
- removed remove_pages() only used in powerpc.
- removed no-op remove_memory() in i386, sh, sparc64, x86_64.
- only powerpc returns -ENOSYS at memory hot remove(no-op). changes it
to return -EINVAL.
Note:
Currently, only ia64 supports CONFIG_MEMORY_HOTREMOVE. I welcome other
archs if there are requirements and testers.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
