On Thu 18-09-14 09:38:05, Wang Nan wrote: > Commit ff7ee93f4 introduces kmemleak_alloc() for alloc_page_cgroup(), > but corresponding kmemleak_free() is missing, which makes kmemleak be > wrongly disabled after memory offlining. Log is pasted at the end of > this commit message. > > This patch add kmemleak_free() into free_page_cgroup(). During page > offlining, this patch removes corresponding entries in kmemleak rbtree. > After that, the freed memory can be allocated again by other subsystems > without killing kmemleak. > > bash # for x in 1 2 3 4; do echo offline > /sys/devices/system/memory/memory$x/state ; sleep 1; done ; dmesg | grep leak > [ 45.537934] Offlined Pages 32768 > [ 46.617892] kmemleak: Cannot insert 0xffff880016969000 into the object search tree (overlaps existing) > [ 46.617892] CPU: 0 PID: 412 Comm: sleep Not tainted 3.17.0-rc5+ #86 > [ 46.617892] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > [ 46.617892] ffff880016823d10 ffff880018bdfc38 ffffffff81725d2c ffff88001780e950 > [ 46.617892] ffff880016969000 ffff880018bdfc88 ffffffff8117a9e6 ffff880018bdfc78 > [ 46.617892] 0000000000000096 ffff880017812800 ffffffff81c2eda0 ffff880016969000 > [ 46.617892] Call Trace: > [ 46.617892] [<ffffffff81725d2c>] dump_stack+0x46/0x58 > [ 46.617892] [<ffffffff8117a9e6>] create_object+0x266/0x2c0 > [ 46.617892] [<ffffffff8171d2f6>] kmemleak_alloc+0x26/0x50 > [ 46.617892] [<ffffffff8116a3a3>] kmem_cache_alloc+0xd3/0x160 > [ 46.617892] [<ffffffff81058e59>] __sigqueue_alloc+0x49/0xd0 > [ 46.617892] [<ffffffff8105a41b>] __send_signal+0xcb/0x410 > [ 46.617892] [<ffffffff8105a7a5>] send_signal+0x45/0x90 > [ 46.617892] [<ffffffff8105a803>] __group_send_sig_info+0x13/0x20 > [ 46.617892] [<ffffffff8105bd0b>] do_notify_parent+0x1bb/0x260 > [ 46.617892] [<ffffffff81077e7a>] ? sched_move_task+0xaa/0x130 > [ 46.617892] [<ffffffff81050917>] do_exit+0x767/0xa40 > [ 46.617892] [<ffffffff81050c84>] do_group_exit+0x44/0xa0 > [ 46.617892] [<ffffffff81050cf7>] SyS_exit_group+0x17/0x20 > [ 46.617892] [<ffffffff8172cd12>] system_call_fastpath+0x16/0x1b > [ 46.617892] kmemleak: Kernel memory leak detector disabled > [ 46.617892] kmemleak: Object 0xffff880016900000 (size 524288): > [ 46.617892] kmemleak: comm "swapper/0", pid 0, jiffies 4294667296 > [ 46.617892] kmemleak: min_count = 0 > [ 46.617892] kmemleak: count = 0 > [ 46.617892] kmemleak: flags = 0x1 > [ 46.617892] kmemleak: checksum = 0 > [ 46.617892] kmemleak: backtrace: > [ 46.617892] [<ffffffff81d0a7f0>] log_early+0x63/0x77 > [ 46.617892] [<ffffffff8171d31b>] kmemleak_alloc+0x4b/0x50 > [ 46.617892] [<ffffffff81720e4f>] init_section_page_cgroup+0x7f/0xf5 > [ 46.617892] [<ffffffff81d0a6f0>] page_cgroup_init+0xc5/0xd0 > [ 46.617892] [<ffffffff81ce4ed9>] start_kernel+0x333/0x408 > [ 46.617892] [<ffffffff81ce45b2>] x86_64_start_reservations+0x2a/0x2c > [ 46.617892] [<ffffffff81ce46a9>] x86_64_start_kernel+0xf5/0xfc > [ 46.617892] [<ffffffffffffffff>] 0xffffffffffffffff > > Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxx> And sorry, I should have noticed that when reviewing the original patch which added kmemleak_alloc. I think this is worth going into stable. The risk is marginal and somebody might be relying on kmemleak even on older kernels when debugging a bug during memory hotplug. Thanks! > --- > mm/page_cgroup.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c > index 3708264..5331c2b 100644 > --- a/mm/page_cgroup.c > +++ b/mm/page_cgroup.c > @@ -171,6 +171,7 @@ static void free_page_cgroup(void *addr) > sizeof(struct page_cgroup) * PAGES_PER_SECTION; > > BUG_ON(PageReserved(page)); > + kmemleak_free(addr); > free_pages_exact(addr, table_size); > } > } > -- > 1.8.4 > -- Michal Hocko SUSE Labs -- 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>