On Fri, 13 Apr 2007 14:49:57 -0700 "H. Peter Anvin" <[EMAIL PROTECTED]> wrote:
> We just discovered that the accounting for initial memory usage > (head.S: INIT_MAP_BEYOND_END) has been way, way off for a very long > time. This patch makes the initial page table not round up to the > nearest 4M boundary, but instead stop dead (and zero the rest of the > final page table) as soon as it hits the configured limit. > > This patch is intended as a debugging aid. If it goes into the > kernel, it should go in at the very beginning of a review cycle, as it > may very well expose real failures (without Jeremy's patch to fix the > accounting, it *will* crash.) > > Signed-off-by: H. Peter Anvin <[EMAIL PROTECTED]> > > diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S > index 3fa7f93..db6735a 100644 > --- a/arch/i386/kernel/head.S > +++ b/arch/i386/kernel/head.S > @@ -131,15 +131,27 @@ page_pde_offset = (__PAGE_OFFSET >> 20); > movl %ecx,page_pde_offset(%edx) /* Store kernel PDE entry */ > addl $4,%edx > movl $1024, %ecx > + /* > + * End condition: we must map up to and including > + * INIT_MAP_BEYOND_END bytes beyond the end of our > + * own page tables; 0x1000 is the size of the page > + * table were about to write, and +0x007 is the > + * attribute bits. > + */ > + leal (INIT_MAP_BEYOND_END+0x1000+0x007)(%edi),%ebp > 11: > stosl > addl $0x1000,%eax > - loop 11b > - /* End condition: we must map up to and including INIT_MAP_BEYOND_END */ > - /* bytes beyond the end of our own page tables; the +0x007 is the > attribute bits */ > - leal (INIT_MAP_BEYOND_END+0x007)(%edi),%ebp > cmpl %ebp,%eax > - jb 10b > + jae 12f > + loop 11b > + jmp 10b > +12: > + /* Clear the remainder of the last page table */ > + decl %ecx > + xorl %eax,%eax > + rep; stosl > + > movl %edi,(init_pg_tables_end - __PAGE_OFFSET) > > xorl %ebx,%ebx /* This is the boot CPU (BSP) */ This patch causes oopses after a minute or so running LTP's ./testcases/bin/growfiles -W gf16 -b -e 1 -i 0 -L 120 -u -g 4090 -T 100 -t 408990 -l -C 10 -c 1000 -S 10 -f Lgf02_ on everyone's favoutite Vaio, configured with http://userweb.kernel.org/~akpm/config-sony.txt BUG: unable to handle kernel paging request at virtual address c084fa8c printing eip: c0174c46 *pde = 0042a027 *pte = 00000000 Oops: 0002 [#1] Modules linked in: ipw2200 sonypi ipv6 autofs4 hidp l2cap bluetooth sunrpc nf_conntrack_netbios_ns ipt_REJECT nf_conntrack_ipv4 xt_state nf_conntrack nfnetlink xt_tcpudp iptable_filter ip_tables x_tables cpufreq_ondemand video sbs button battery asus_acpi ac nvram ohci1394 ieee1394 ehci_hcd uhci_hcd sg joydev snd_hda_intel snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss sr_mod snd_pcm cdrom ieee80211 ieee80211_crypt snd_timer piix snd soundcore snd_page_alloc i2c_i801 generic i2c_core pcspkr ext3 jbd ide_disk ide_core CPU: 0 EIP: 0060:[<c0174c46>] Not tainted VLI EFLAGS: 00010212 (2.6.21-rc7 #13) EIP is at __block_prepare_write+0x246/0x445 eax: 00000000 ebx: c084f000 ecx: 0000015d edx: 00000574 esi: 00000000 edi: c084fa8c ebp: 00000000 esp: f51e3bc8 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process growfiles (pid: 2913, ti=f51e2000 task=f5f31340 task.ti=f51e2000) Stack: c08317b8 00000001 0000000a 00000000 c08317f0 f6c0f9b0 00000980 00000574 f58953d8 00000000 c10109e0 f7dbb0d8 00005e1a 00000000 00001000 c08317b8 f51e3c24 fffff000 00000000 01000286 00001000 00001000 0000000a f58953d8 Call Trace: [<c0174e67>] block_prepare_write+0x22/0x30 [<f8b853b8>] ext3_get_block+0x0/0xd0 [ext3] [<f8b866e2>] ext3_prepare_write+0x0/0x151 [ext3] [<f8b86778>] ext3_prepare_write+0x96/0x151 [ext3] [<f8b853b8>] ext3_get_block+0x0/0xd0 [ext3] [<f8b866e2>] ext3_prepare_write+0x0/0x151 [ext3] [<c0142832>] generic_file_buffered_write+0x26d/0x5eb [<c024d691>] ata_altstatus+0x1d/0x24 [<c011e314>] current_fs_time+0x37/0x3c [<c0143096>] __generic_file_aio_write_nolock+0x4e6/0x562 [<f8b91728>] ext3_permission+0x0/0xa [ext3] [<c02e3322>] __mutex_lock_slowpath+0x1ac/0x1b4 [<c0143173>] generic_file_aio_write+0x61/0xc1 [<f8b82dfc>] ext3_file_write+0x24/0x90 [ext3] [<c015a444>] do_sync_write+0xc7/0x10a [<c012907c>] autoremove_wake_function+0x0/0x35 [<c015a37d>] do_sync_write+0x0/0x10a [<c015ac89>] vfs_write+0xa8/0x155 [<c015b1c5>] sys_write+0x41/0x67 [<c0163e2a>] sys_fcntl64+0x7d/0x87 [<c0103b68>] syscall_call+0x7/0xb ======================= Code: fa ff 80 7c 24 4f 00 89 c3 74 2f 8b 54 24 50 2b 94 24 80 00 00 00 8b 84 24 80 00 00 00 89 d1 89 54 24 1c c1 e9 02 8d 3c 03 89 f0 <f3> ab f6 c2 02 74 02 66 ab f6 c2 01 74 01 aa 80 7c 24 4e 00 74 EIP: [<c0174c46>] __block_prepare_write+0x246/0x445 SS:ESP 0068:f51e3bc8 note: growfiles[2913] exited with preempt_count 1 BUG: unable to handle kernel paging request at virtual address c0850048 Dropped, with alacrity, at 4:47AM. 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