linux-kernel - [PATCH][RESEND] nommu: yield CPU periodically while disposing large VM

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-next>] [day] [month] [year] [list]

Date:	Thu, 11 Nov 2010 14:33:16 -0600
From:	"Steven J. Magnani" <steve@...idescorp.com>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org,
	"Steven J. Magnani" <steve@...idescorp.com>
Subject: [PATCH][RESEND] nommu: yield CPU periodically while disposing large VM

Depending on processor speed, page size, and the amount of memory a process
is allowed to amass, cleanup of a large VM may freeze the system for many
seconds. This can result in a watchdog timeout.

Make sure other tasks receive some service when cleaning up large VMs.

Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
---
diff -uprN a/mm/nommu.c b/mm/nommu.c
--- a/mm/nommu.c	2010-10-21 07:42:23.000000000 -0500
+++ b/mm/nommu.c	2010-10-21 07:46:50.000000000 -0500
@@ -1656,6 +1656,7 @@ SYSCALL_DEFINE2(munmap, unsigned long, a
 void exit_mmap(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
+	unsigned long next_yield = jiffies + HZ;
 
 	if (!mm)
 		return;
@@ -1668,6 +1669,11 @@ void exit_mmap(struct mm_struct *mm)
 		mm->mmap = vma->vm_next;
 		delete_vma_from_mm(vma);
 		delete_vma(mm, vma);
+		/* Yield periodically to prevent watchdog timeout */
+		if (time_after(jiffies, next_yield)) {
+			cond_resched();
+			next_yield = jiffies + HZ;
+		}
 	}
 
 	kleave("");

--
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/