On Tue, Jun 21, 2016 at 11:19:07PM +0800, zhong jiang wrote: > On 2016/6/21 22:37, Kirill A. Shutemov wrote: > > On Tue, Jun 21, 2016 at 10:05:56PM +0800, zhongjiang wrote: > >> From: zhong jiang <zhongjiang@xxxxxxxxxx> > >> > >> with great pressure, I run some test cases. As a result, I found > >> that the THP is not freed, it is detected by check_mm(). > >> > >> BUG: Bad rss-counter state mm:ffff8827edb70000 idx:1 val:512 > >> > >> Consider the following race : > >> > >> CPU0 CPU1 > >> __handle_mm_fault() > >> wp_huge_pmd() > >> do_huge_pmd_wp_page() > >> pmdp_huge_clear_flush_notify() > >> (pmd_none = true) > >> exit_mmap() > >> unmap_vmas() > >> zap_pmd_range() > >> pmd_none_or_trans_huge_or_clear_bad() > >> (result in memory leak) > >> set_pmd_at() > >> > >> because of CPU0 have allocated huge page before pmdp_huge_clear_notify, > >> and it make the pmd entry to be null. Therefore, The memory leak can occur. > >> > >> The patch fix the scenario that the pmd entry can lead to be null. > > I don't think the scenario is possible. > > > > exit_mmap() called when all mm users have gone, so no parallel threads > > exist. > > > Forget this patch. It 's my fault , it indeed don not exist. > But I hit the following problem. we can see the memory leak when the process exit. > > > Any suggestion will be apprecaited. Could you try this: http://lkml.kernel.org/r/20160621150433.GA7536@xxxxxxxxxxxxxxxxxx -- Kirill A. Shutemov -- 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>