Interesting. I got tested with #define MAX_PHYSMEM_BITS 31 #define SECTION_SIZE_BITS 27
# cat /proc/sys/vm/min_free_kbytes 1832 # echo 1828 > /proc/sys/vm/min_free_kbytes # cat /proc/sys/vm/min_free_kbytes 1828 # echo 1820 > /proc/sys/vm/min_free_kbytes # cat /proc/sys/vm/min_free_kbytes 1820 # echo 1700 > /proc/sys/vm/min_free_kbytes # cat /proc/sys/vm/min_free_kbytes 1700 No kernel panic. Thank you, Kyungmin Park On Mon, Jul 12, 2010 at 5:32 PM, Kukjin Kim <kgene....@samsung.com> wrote: > Russell, > > Hi, > > Kukjin Kim wrote: >> Russell wrote: >> > So, memory starts at 0x20000000 and finishes at 0x25000000. That's > fine. >> > That doesn't mean the section size is 16MB. >> > >> > As I've already said, the section size has _nothing_ what so ever to do >> > with the size of memory, or the granularity of the size of memory. By >> > way of illustration, it is perfectly legal to have a section size of >> > 256MB but only have 1MB in a section and this is perfectly legal. So >> > sections do not have to be completely filled. >> > >> Actually, as you know, the hole's area of mem_map is freed from bootmem if > a >> section has a hole when initializing sparse memory. >> >> I identified that a section doesn't need to be a contiguous area of > physical >> memory when reading your comment with the fact that the mem_map of a > section >> can be smaller than the size of a section. >> >> I found, however, the kernel panics when modifying min_free_kbytes file in >> the proc filesystem if a section has a hole. >> >> While processing the change of min_free_kbytes in the kernel, page >> descriptors in a hole of an online section is accessed. > > As I said, following error happens. > It would be helpful to me if any opinions or comments. > > --- > When SECTION_SIZE_BITS is 24 (16MiB), > > [r...@samsung ~]# cat /proc/sys/vm/min_free_kbytes > 2736 > [r...@samsung ~]# echo "2730" > /proc/sys/vm/min_free_kbytes > > [r...@samsung ~]# cat /proc/sys/vm/min_free_kbytes > 2730 > [r...@samsung ~]# > > > When SECTION_SIZE_BITS is 28 (256MiB), > > [r...@samsung ~]# cat /proc/sys/vm/min_free_kbytes > 2736 > [r...@samsung ~]# echo "2730" > /proc/sys/vm/min_free_kbytes > Unable to handle kernel NULL pointer dereference at virtual address 00000004 > pgd = 80a14000 > [00000004] *pgd=20a0b031, *pte=00000000, *ppte=00000000 > Internal error: Oops: 17 [#1] PREEMPT > last sysfs file: > Modules linked in: > CPU: 0 Not tainted (2.6.35-rc4-00007-g9a59bf7-dirty #3) > PC is at get_pageblock_flags_group+0x54/0xa8 > LR is at setup_per_zone_wmarks+0xfc/0x1d4 > pc : [<800686cc>] lr : [<800691a0>] psr: 60000093 > sp : 80a03ed0 ip : 00000001 fp : 00058000 > r10: 004a0000 r9 : 801e5fbc r8 : 802c0000 > r7 : 0001c900 r6 : 00025000 r5 : 801e5fa4 r4 : 0000007e > r3 : 00000018 r2 : 00000002 r1 : 00000000 r0 : 00000000 > Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment user > Control: 10c5387d Table: 20a14019 DAC: 00000015 > Process bash (pid: 888, stack limit = 0x80a022e8) > Stack: (0x80a03ed0 to 0x80a04000) > 3ec0: 00000000 801e5fa4 00025000 > 800691a0 > 3ee0: a0000013 000002aa 00000005 00000001 801d8254 2aacb000 00000005 > 00000001 > 3f00: 80a02000 80a03f80 00000001 80069354 80a03f80 00000001 801d7900 > 800d2734 > 3f20: 80a03f80 00000000 00000000 00000005 80a0903c 00000005 b7c81c00 > 2aacb000 > 3f40: 80a03f80 00000005 00000000 800d2760 00000001 2aacb000 00000005 > 8008ff74 > 3f60: b7c81c00 2aacb000 b7c81c00 2aacb000 00000000 00000000 00000005 > 800900c8 > 3f80: 00000005 00000000 00000005 00000000 00000005 2aacb000 2ac525f8 > 00000004 > 3fa0: 8001f0e8 8001ef40 00000005 2aacb000 00000001 2aacb000 00000005 > 00000000 > 3fc0: 00000005 2aacb000 2ac525f8 00000004 00000005 000babe0 00000000 > 00000001 > 3fe0: 2aacb000 7e88ca58 2ab99124 2abe643c 60000010 00000001 00000000 > 00000000 > [<800686cc>] (get_pageblock_flags_group+0x54/0xa8) from [<800691a0>] > (setup_per_zone_wmarks+0xfc/0x1d4) > [<800691a0>] (setup_per_zone_wmarks+0xfc/0x1d4) from [<80069354>] > (min_free_kbytes_sysctl_handler+0x20/0x28) > [<80069354>] (min_free_kbytes_sysctl_handler+0x20/0x28) from [<800d2734>] > (proc_sys_call_handler+0x90/0xac) > [<800d2734>] (proc_sys_call_handler+0x90/0xac) from [<800d2760>] > (proc_sys_write+0x10/0x14) > [<800d2760>] (proc_sys_write+0x10/0x14) from [<8008ff74>] > (vfs_write+0xac/0x154) > [<8008ff74>] (vfs_write+0xac/0x154) from [<800900c8>] (sys_write+0x3c/0x68) > [<800900c8>] (sys_write+0x3c/0x68) from [<8001ef40>] > (ret_fast_syscall+0x0/0x30) > Code: 11a0cb8c 11a0cbac 1080018c e3a0c001 (e5904004) > ---[ end trace 8b96cc6afed783d1 ]--- > note: bash[888] exited with preempt_count 1 > BUG: scheduling while atomic: bash/888/0x40000002 > Modules linked in: > [<80024558>] (unwind_backtrace+0x0/0xec) from [<8014f110>] > (schedule+0x6c/0x2e4) > [<8014f110>] (schedule+0x6c/0x2e4) from [<80035f74>] > (__cond_resched+0x24/0x34) > [<80035f74>] (__cond_resched+0x24/0x34) from [<8014f484>] > (_cond_resched+0x30/0x40) > [<8014f484>] (_cond_resched+0x30/0x40) from [<8007ac1c>] > (unmap_vmas+0x550/0x604) > [<8007ac1c>] (unmap_vmas+0x550/0x604) from [<8007d6b8>] > (exit_mmap+0xb0/0x1d8) > [<8007d6b8>] (exit_mmap+0xb0/0x1d8) from [<80037de8>] (mmput+0x4c/0x104) > [<80037de8>] (mmput+0x4c/0x104) from [<8003b7f4>] (exit_mm+0x104/0x10c) > [<8003b7f4>] (exit_mm+0x104/0x10c) from [<8003cdc4>] (do_exit+0x194/0x5bc) > [<8003cdc4>] (do_exit+0x194/0x5bc) from [<80022950>] (die+0x190/0x1bc) > [<80022950>] (die+0x190/0x1bc) from [<80025488>] > (__do_kernel_fault+0x64/0x84) > [<80025488>] (__do_kernel_fault+0x64/0x84) from [<8002567c>] > (do_page_fault+0x1d4/0x1ec) > [<8002567c>] (do_page_fault+0x1d4/0x1ec) from [<8001e2d0>] > (do_DataAbort+0x34/0x94) > [<8001e2d0>] (do_DataAbort+0x34/0x94) from [<8001ea2c>] > (__dabt_svc+0x4c/0x60) > Exception stack(0x80a03e88 to 0x80a03ed0) > 3e80: 00000000 00000000 00000002 00000018 0000007e > 801e5fa4 > 3ea0: 00025000 0001c900 802c0000 801e5fbc 004a0000 00058000 00000001 > 80a03ed0 > 3ec0: 800691a0 800686cc 60000093 ffffffff > [<8001ea2c>] (__dabt_svc+0x4c/0x60) from [<800686cc>] > (get_pageblock_flags_group+0x54/0xa8) > [<800686cc>] (get_pageblock_flags_group+0x54/0xa8) from [<800691a0>] > (setup_per_zone_wmarks+0xfc/0x1d4) > [<800691a0>] (setup_per_zone_wmarks+0xfc/0x1d4) from [<80069354>] > (min_free_kbytes_sysctl_handler+0x20/0x28) > [<80069354>] (min_free_kbytes_sysctl_handler+0x20/0x28) from [<800d2734>] > (proc_sys_call_handler+0x90/0xac) > [<800d2734>] (proc_sys_call_handler+0x90/0xac) from [<800d2760>] > (proc_sys_write+0x10/0x14) > [<800d2760>] (proc_sys_write+0x10/0x14) from [<8008ff74>] > (vfs_write+0xac/0x154) > [<8008ff74>] (vfs_write+0xac/0x154) from [<800900c8>] (sys_write+0x3c/0x68) > [<800900c8>] (sys_write+0x3c/0x68) from [<8001ef40>] > (ret_fast_syscall+0x0/0x30) > BUG: spinlock lockup on CPU#0, bash/888, 801e5fbc > [<80024558>] (unwind_backtrace+0x0/0xec) from [<801098a8>] > (do_raw_spin_lock+0x110/0x14c) > [<801098a8>] (do_raw_spin_lock+0x110/0x14c) from [<8006963c>] > (free_pcppages_bulk+0x24/0x2f4) > [<8006963c>] (free_pcppages_bulk+0x24/0x2f4) from [<80069f28>] > (free_hot_cold_page+0x15c/0x180) > [<80069f28>] (free_hot_cold_page+0x15c/0x180) from [<8007b834>] > (free_pgd_range+0x15c/0x17c) > [<8007b834>] (free_pgd_range+0x15c/0x17c) from [<8007b8e4>] > (free_pgtables+0x90/0x9c) > [<8007b8e4>] (free_pgtables+0x90/0x9c) from [<8007d714>] > (exit_mmap+0x10c/0x1d8) > [<8007d714>] (exit_mmap+0x10c/0x1d8) from [<80037de8>] (mmput+0x4c/0x104) > [<80037de8>] (mmput+0x4c/0x104) from [<8003b7f4>] (exit_mm+0x104/0x10c) > [<8003b7f4>] (exit_mm+0x104/0x10c) from [<8003cdc4>] (do_exit+0x194/0x5bc) > [<8003cdc4>] (do_exit+0x194/0x5bc) from [<80022950>] (die+0x190/0x1bc) > [<80022950>] (die+0x190/0x1bc) from [<80025488>] > (__do_kernel_fault+0x64/0x84) > [<80025488>] (__do_kernel_fault+0x64/0x84) from [<8002567c>] > (do_page_fault+0x1d4/0x1ec) > [<8002567c>] (do_page_fault+0x1d4/0x1ec) from [<8001e2d0>] > (do_DataAbort+0x34/0x94) > [<8001e2d0>] (do_DataAbort+0x34/0x94) from [<8001ea2c>] > (__dabt_svc+0x4c/0x60) > Exception stack(0x80a03e88 to 0x80a03ed0) > 3e80: 00000000 00000000 00000002 00000018 0000007e > 801e5fa4 > 3ea0: 00025000 0001c900 802c0000 801e5fbc 004a0000 00058000 00000001 > 80a03ed0 > 3ec0: 800691a0 800686cc 60000093 ffffffff > [<8001ea2c>] (__dabt_svc+0x4c/0x60) from [<800686cc>] > (get_pageblock_flags_group+0x54/0xa8) > [<800686cc>] (get_pageblock_flags_group+0x54/0xa8) from [<800691a0>] > (setup_per_zone_wmarks+0xfc/0x1d4) > [<800691a0>] (setup_per_zone_wmarks+0xfc/0x1d4) from [<80069354>] > (min_free_kbytes_sysctl_handler+0x20/0x28) > [<80069354>] (min_free_kbytes_sysctl_handler+0x20/0x28) from [<800d2734>] > (proc_sys_call_handler+0x90/0xac) > [<800d2734>] (proc_sys_call_handler+0x90/0xac) from [<800d2760>] > (proc_sys_write+0x10/0x14) > [<800d2760>] (proc_sys_write+0x10/0x14) from [<8008ff74>] > (vfs_write+0xac/0x154) > [<8008ff74>] (vfs_write+0xac/0x154) from [<800900c8>] (sys_write+0x3c/0x68) > [<800900c8>] (sys_write+0x3c/0x68) from [<8001ef40>] > (ret_fast_syscall+0x0/0x30) > > > Thanks. > > Best regards, > Kgene. > -- > Kukjin Kim <kgene....@samsung.com>, Senior Engineer, > SW Solution Development Team, Samsung Electronics Co., Ltd. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" > in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
