Hi all, While fuzzing with trinity inside a KVM tools guest running the latest -next kernel I've stumbled on the following. Out of curiosity, is there a reason not to do bad flag checks when actually setting flag? Obviously it'll be slower but it'll be easier catching these issues. [ 3926.683948] BUG: Bad page state in process ksmd pfn:5a6246 [ 3926.689336] page:ffffea0016989180 count:0 mapcount:0 mapping: (null) index: [ 3926.696507] page flags: 0x56fffff8028001c(referenced|uptodate|dirty|swapbacked|mlock [ 3926.709201] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set [ 3926.711216] bad because of flags: [ 3926.712136] page flags: 0x200000(mlocked) [ 3926.713574] Modules linked in: [ 3926.714466] CPU: 26 PID: 3864 Comm: ksmd Tainted: G W 3.14.0-rc7-next-201 [ 3926.720942] ffffffff85688060 ffff8806ec7abc38 ffffffff844bd702 0000000000002fa0 [ 3926.728107] ffffea0016989180 ffff8806ec7abc68 ffffffff844b158f 000fffff80000000 [ 3926.730563] 0000000000000000 000fffff80000000 ffffffff85688060 ffff8806ec7abcb8 [ 3926.737653] Call Trace: [ 3926.738347] dump_stack (lib/dump_stack.c:52) [ 3926.739841] bad_page (arch/x86/include/asm/atomic.h:38 include/linux/mm.h:432 mm/page_alloc.c:339) [ 3926.741296] free_pages_prepare (mm/page_alloc.c:644 mm/page_alloc.c:738) [ 3926.742818] free_hot_cold_page (mm/page_alloc.c:1371) [ 3926.749425] __put_single_page (mm/swap.c:71) [ 3926.751074] put_page (mm/swap.c:237) [ 3926.752398] ksm_do_scan (mm/ksm.c:1480 mm/ksm.c:1704) [ 3926.753957] ksm_scan_thread (mm/ksm.c:1723) [ 3926.755940] ? bit_waitqueue (kernel/sched/wait.c:291) [ 3926.758644] ? ksm_do_scan (mm/ksm.c:1715) [ 3926.760420] kthread (kernel/kthread.c:219) [ 3926.761605] ? kthread_create_on_node (kernel/kthread.c:185) [ 3926.763149] ret_from_fork (arch/x86/kernel/entry_64.S:555) [ 3926.764323] ? kthread_create_on_node (kernel/kthread.c:185) Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>