From ef9956380360aaffd9ca9dde20d8a74f22c4cc8c Mon Sep 17 00:00:00 2001 From: Wu Zhangjin Date: Fri, 4 Sep 2009 11:22:02 +0800 Subject: [PATCH] mm: Fix the non-RT version of swap_get_cpu_var commit edc1a1c366af0d1c755f159b3ac503812e166173 in tip. The commit(f8382688) have converted swap to percpu locked, the non-RT version of swap_get_cpu_var should be the same as the old implementation, but in reality, it not works as the old one: ... +#define swap_get_cpu_var(var, cpu) \ + ({ \ + (void)cpu; \ + &get_cpu_var(var); \ + }) ... void __lru_cache_add(struct page *page, enum lru_list lru) { - struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru]; + struct pagevec *pvec; + int cpu; + pvec = swap_get_cpu_var(lru_add_pvecs, cpu)[lru]; page_cache_get(page); if (!pagevec_add(pvec, page)) ____pagevec_lru_add(pvec, lru); - put_cpu_var(lru_add_pvecs); + swap_put_cpu_var(lru_add_pvecs, cpu); } Here is the point, the old version: pvec = &get_cpu_var(lru_add_pvecs)[lru]; = & (get_cpu_var(lru_add_pvecs)[lru]); new version from commit f8382688: pvec = ({ (void)cpu; &get_cpu_var(lru_add_pvecs); })[lru]; = (&get_cpu_var(lru_add_pvecs)) [lru]; so, we can see, these two are really different. and it made the non-RT boot fail: ... ide-gd driver 1.18 hda: max request size: 512KiB hda: 312581808 sectors (160041 MB) w/8192KiB Cache, CHS=19457/255/63 hda: cache flushes supported hda:Unhandled kernel unaligned access[#1]: Cpu 0 $ 0 : 0000000000000000 000000001400c4e1 98000000013699d0 0000000000000000 $ 4 : 0000000000000000 98000000be04f980 0000000000000010 000000007fd78b57 $ 8 : 0000000000000001 0000000000200200 0000000000100100 98000000be00f210 $12 : 000000001400c4e1 000000001000001e ffffffffffffffff 98000000bd0180a8 $16 : 0000000000000000 98000000be04f998 fffffffb81a72600 ffffffff802d3270 $20 : 0000000000000000 0000000000000000 ffffffffffffffef ffffffff80667a90 $24 : 0000000000000228 ffffffff803ded88 $28 : 98000000be04c000 98000000be04f950 00000000003fffff ffffffff80200404 Hi : 0000000000000000 Lo : 0000000000000320 epc : ffffffff80217194 do_ade+0x298/0x3bc Not tainted ra : ffffffff80200404 ret_from_exception+0x0/0x10 Status: 1400c4e3 KX SX UX KERNEL EXL IE Cause : 00000014 BadVA : fffffffb81a72607 PrId : 00006303 (ICT Loongson-2) Modules linked in: Process swapper (pid: 1, threadinfo=98000000be04c000, task=98000000be04b7d8, tls=0000000000000000) Stack : ffffffff80666f60 ffffffff8025165c 98000000013699d0 0000000000000001 98000000bd00ae30 ffffffff80200404 0000000000000000 000000001400c4e1 000000007fd78b57 98000000013699d0 ffffffff80638070 0000000000000002 fffffffb81a72600 000000007fd78b57 0000000000000001 0000000000200200 0000000000100100 98000000be00f210 98000000be00f220 000000000000001d ffffffffffffffff 98000000bd0180a8 98000000013699d0 0000000000000001 98000000bd00ae30 ffffffff802d3270 0000000000000000 0000000000000000 ffffffffffffffef ffffffff80667a90 0000000000000228 ffffffff803ded88 98000000bd00ae30 98000000bd00ae30 98000000be04c000 98000000be04fab0 00000000003fffff ffffffff80275350 000000001400c4e3 0000000000000000 ... Call Trace: [] do_ade+0x298/0x3bc [] ret_from_exception+0x0/0x10 [] __lru_cache_add+0x94/0xd8 [] add_to_page_cache_lru+0x84/0xa8 [] read_cache_page_async+0xa8/0x1dc [] read_cache_page+0x10/0x74 [] read_dev_sector+0x34/0xe0 [] adfspart_check_ICS+0x44/0x1b0 [] rescan_partitions+0x178/0x3a8 [] __blkdev_get+0x238/0x318 [] register_disk+0xd0/0x15c [] add_disk+0xcc/0x128 [] ide_gd_probe+0x170/0x1d0 [] driver_probe_device+0xbc/0x180 [] __driver_attach+0x6c/0xa4 [] bus_for_each_dev+0x58/0xa4 [] bus_add_driver+0xc8/0x284 [] driver_register+0xc4/0x17c [] do_one_initcall+0x64/0x18c [] kernel_init+0xe0/0x14c [] kernel_thread_helper+0x10/0x18 Code: 001188f8 00b1882d de220000 b6420000 24120000 1640000c 00a0202d 8ca20120 Disabling lock debugging due to kernel taint note: swapper[1] exited with preempt_count 1 Kernel panic - not syncing: Attempted to kill init! This patch will keep the swap_get_cpu_var as the one before commit f8382688, and put "(void)cpu;" to swap_put_cpu_var() to avoid warning about unused variable. Signed-off-by: Wu Zhangjin LKML-Reference: <1252034522-32653-1-git-send-email-wuzhangjin@gmail.com> Signed-off-by: Thomas Gleixner Signed-off-by: Paul Gortmaker --- mm/swap.c | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index 3f917bb..fbabfc3 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -96,12 +96,13 @@ static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); local_irq_restore(flags) #define swap_get_cpu_var(var, cpu) \ - ({ \ - (void)cpu; \ - &get_cpu_var(var); \ - }) + &get_cpu_var(var) \ -#define swap_put_cpu_var(var, cpu) put_cpu_var(var) +#define swap_put_cpu_var(var, cpu) \ + ({ \ + (void)cpu; \ + put_cpu_var(var); \ + }) #define swap_per_cpu_lock(var, cpu) &per_cpu(var, cpu) -- 1.7.0.4