The patch titled
printk() should not be called under zone->lock
has been added to the -mm tree. Its filename is
printk-should-not-be-called-under-zone-lock.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: printk() should not be called under zone->lock
From: Kirill Korotaev <dev@xxxxxxxxxx>
This patch fixes printk() under zone->lock in show_free_areas(). It can be
unsafe to call printk() under this lock, since caller can try to
allocate/free some memory and selfdeadlock on this lock. I found
allocations/freeing mem both in netconsole and serial console.
This issue was faced in reallity when meminfo was periodically printed for
debug purposes and netconsole was used.
Signed-off-by: Kirill Korotaev <dev@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/page_alloc.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff -puN mm/page_alloc.c~printk-should-not-be-called-under-zone-lock mm/page_alloc.c
--- a/mm/page_alloc.c~printk-should-not-be-called-under-zone-lock
+++ a/mm/page_alloc.c
@@ -1506,7 +1506,7 @@ void show_free_areas(void)
}
for_each_zone(zone) {
- unsigned long nr, flags, order, total = 0;
+ unsigned long nr[MAX_ORDER], flags, order, total = 0;
show_node(zone);
printk("%s: ", zone->name);
@@ -1517,11 +1517,12 @@ void show_free_areas(void)
spin_lock_irqsave(&zone->lock, flags);
for (order = 0; order < MAX_ORDER; order++) {
- nr = zone->free_area[order].nr_free;
- total += nr << order;
- printk("%lu*%lukB ", nr, K(1UL) << order);
+ nr[order] = zone->free_area[order].nr_free;
+ total += nr[order] << order;
}
spin_unlock_irqrestore(&zone->lock, flags);
+ for (order = 0; order < MAX_ORDER; order++)
+ printk("%lu*%lukB ", nr[order], K(1UL) << order);
printk("= %lukB\n", K(total));
}
_
Patches currently in -mm which might be from dev@xxxxxxxxxx are
printk-should-not-be-called-under-zone-lock.patch
fix-dcache-race-during-umount.patch
prune_one_dentry-tweaks.patch
proc-sysctl-add-_proc_do_string-helper.patch
namespaces-add-nsproxy.patch
namespaces-add-nsproxy-dont-include-compileh.patch
namespaces-incorporate-fs-namespace-into-nsproxy.patch
namespaces-utsname-introduce-temporary-helpers.patch
namespaces-utsname-switch-to-using-uts-namespaces.patch
namespaces-utsname-switch-to-using-uts-namespaces-alpha-fix.patch
namespaces-utsname-switch-to-using-uts-namespaces-cleanup.patch
namespaces-utsname-use-init_utsname-when-appropriate.patch
namespaces-utsname-use-init_utsname-when-appropriate-cifs-update.patch
namespaces-utsname-implement-utsname-namespaces.patch
namespaces-utsname-implement-utsname-namespaces-export.patch
namespaces-utsname-implement-utsname-namespaces-dont-include-compileh.patch
namespaces-utsname-sysctl-hack.patch
namespaces-utsname-sysctl-hack-cleanup.patch
namespaces-utsname-sysctl-hack-cleanup-2.patch
namespaces-utsname-sysctl-hack-cleanup-2-fix.patch
namespaces-utsname-remove-system_utsname.patch
namespaces-utsname-implement-clone_newuts-flag.patch
uts-copy-nsproxy-only-when-needed.patch
ipc-namespace-core.patch
ipc-namespace-core-fix.patch
ipc-namespace-core-unshare-fix.patch
ipc-namespace-utils.patch
ipc-namespace-msg.patch
ipc-namespace-sem.patch
ipc-namespace-shm.patch
ipc-namespace-sysctls.patch
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