linux-kernel - Re: [PATCH 53 of 66] add numa awareness to hugepage allocations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 30 Nov 2010 20:01:59 +0100
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc:	linux-mm@...ck.org, Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Adam Litke <agl@...ibm.com>, Avi Kivity <avi@...hat.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...e.hu>, Mike Travis <travis@....com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Chris Wright <chrisw@...s-sol.org>, bpicco@...hat.com,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Chris Mason <chris.mason@...cle.com>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 53 of 66] add numa awareness to hugepage allocations

On Tue, Nov 30, 2010 at 09:38:04AM +0900, Daisuke Nishimura wrote:
> I'm sorry if I miss something, "new_page" will be reused in !CONFIG_NUMA case
> as you say, but, in CONFIG_NUMA case, it is allocated in this function
> (collapse_huge_page()) by alloc_hugepage_vma(), and is not freed when memcg's
> charge failed.
> Actually, we do in collapse_huge_page():
> 	if (unlikely(!isolated)) {
> 		...
> #ifdef CONFIG_NUMA
> 		put_page(new_page);
> #endif
> 		goto out;
> 	}
> later. I think we need a similar logic in memcg's failure path too.

Apologies, you really found a minor memleak in case of memcg
accounting failure.

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1726,7 +1726,7 @@ static void collapse_huge_page(struct mm
 	}
 #endif
 	if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
-		goto out;
+		goto out_put_page;
 
 	anon_vma_lock(vma->anon_vma);
 
@@ -1755,10 +1755,7 @@ static void collapse_huge_page(struct mm
 		spin_unlock(&mm->page_table_lock);
 		anon_vma_unlock(vma->anon_vma);
 		mem_cgroup_uncharge_page(new_page);
-#ifdef CONFIG_NUMA
-		put_page(new_page);
-#endif
-		goto out;
+		goto out_put_page;
 	}
 
 	/*
@@ -1799,6 +1796,13 @@ static void collapse_huge_page(struct mm
 	khugepaged_pages_collapsed++;
 out:
 	up_write(&mm->mmap_sem);
+	return;
+
+out_put_page:
+#ifdef CONFIG_NUMA
+	put_page(new_page);
+#endif
+	goto out;
 }
 
 static int khugepaged_scan_pmd(struct mm_struct *mm,



I was too optimistic that there wasn't really a bug, I thought it was
some confusion about the hpage usage that differs with numa and not
numa.

On a side note, the CONFIG_NUMA case will later change further to move
the allocation out of the mmap_sem write mode to make the fs
submitting I/O from userland and doing memory allocations in the I/O
paths happier.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/