Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751997AbbFMHrJ (ORCPT ); Sat, 13 Jun 2015 03:47:09 -0400 Received: from mail-wg0-f42.google.com ([74.125.82.42]:33411 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127AbbFMHrB (ORCPT ); Sat, 13 Jun 2015 03:47:01 -0400 Date: Sat, 13 Jun 2015 09:46:55 +0200 From: Ingo Molnar To: Waiman Long Cc: linux-kernel@vger.kernel.org, linux-mml@vger.kernel.org, Andy Lutomirski , Andrew Morton , Denys Vlasenko , Brian Gerst , Peter Zijlstra , Borislav Petkov , "H. Peter Anvin" , Linus Torvalds , Oleg Nesterov , Thomas Gleixner Subject: Re: [PATCH 02/12] x86/mm/hotplug: Remove pgd_list use from the memory hotplug code Message-ID: <20150613074655.GB30388@gmail.com> References: <1434031637-9091-1-git-send-email-mingo@kernel.org> <1434031637-9091-3-git-send-email-mingo@kernel.org> <557B61B7.4080301@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <557B61B7.4080301@hp.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1778 Lines: 51 * Waiman Long wrote: > >@@ -169,29 +169,33 @@ void sync_global_pgds(unsigned long start, unsigned long end, int removed) > > > > for (address = start; address<= end; address += PGDIR_SIZE) { > > const pgd_t *pgd_ref = pgd_offset_k(address); > >- struct page *page; > >+ struct task_struct *g, *p; > > > > /* > >- * When it is called after memory hot remove, pgd_none() > >- * returns true. In this case (removed == 1), we must clear > >- * the PGD entries in the local PGD level page. > >+ * When this function is called after memory hot remove, > >+ * pgd_none() already returns true, but only the reference > >+ * kernel PGD has been cleared, not the process PGDs. > >+ * > >+ * So clear the affected entries in every process PGD as well: > > */ > > if (pgd_none(*pgd_ref)&& !removed) > > continue; > > > > spin_lock(&pgd_lock); > >- list_for_each_entry(page,&pgd_list, lru) { > >- pgd_t *pgd; > >+ > >+ for_each_process_thread(g, p) { > >+ pgd_t *pgd = p->mm->pgd; > > spinlock_t *pgt_lock; > > > >- pgd = (pgd_t *)page_address(page) + pgd_index(address); > >- /* the pgt_lock only for Xen */ > >- pgt_lock =&pgd_page_get_mm(page)->page_table_lock; > >+ if (!p->mm) > >+ continue; > > pgd was initialized to p->mm->pgd before the "p->mm" check is done. > Shouldn't the initialization be moved after that. Yes, already found this bug in testing and fixed it - will send out a new series with all the feedback so far addressed. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/