The patch titled
Subject: idr: idr_alloc() shouldn't trigger lowmem warning when preloaded
has been added to the -mm tree. Its filename is
idr-idr_alloc-shouldnt-trigger-lowmem-warning-when-preloaded.patch
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------------------------------------------------------
From: Tejun Heo <tj@xxxxxxxxxx>
Subject: idr: idr_alloc() shouldn't trigger lowmem warning when preloaded
GFP_NOIO is often used for idr_alloc() inside preloaded section as the
allocation mask doesn't really matter. If the idr tree needs to be
expanded, idr_alloc() first tries to allocate using the specified
allocation mask and if it fails falls back to the preloaded buffer. This
order prevent non-preloading idr_alloc() users from taking advantage of
preloading ones by using preload buffer without filling it shifting the
burden of allocation to the preload users.
Unfortunately, this allowed/expected-to-fail kmem_cache allocation ends up
generating spurious slab lowmem warning before succeeding the request from
the preload buffer.
This patch makes idr_layer_alloc() add __GFP_NOWARN to the first
kmem_cache attempt and try kmem_cache again w/o __GFP_NOWARN after
allocation from preload_buffer fails so that lowmem warning is generated
if not suppressed by the original @gfp_mask.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: David Teigland <teigland@xxxxxxxxxx>
Tested-by: David Teigland <teigland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/idr.c | 38 +++++++++++++++++++++++++-------------
1 file changed, 25 insertions(+), 13 deletions(-)
diff -puN lib/idr.c~idr-idr_alloc-shouldnt-trigger-lowmem-warning-when-preloaded lib/idr.c
--- a/lib/idr.c~idr-idr_alloc-shouldnt-trigger-lowmem-warning-when-preloaded
+++ a/lib/idr.c
@@ -106,8 +106,14 @@ static struct idr_layer *idr_layer_alloc
if (layer_idr)
return get_from_free_list(layer_idr);
- /* try to allocate directly from kmem_cache */
- new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
+ /*
+ * Try to allocate directly from kmem_cache. We want to try this
+ * before preload buffer; otherwise, non-preloading idr_alloc()
+ * users will end up taking advantage of preloading ones. As the
+ * following is allowed to fail for preloaded cases, suppress
+ * warning this time.
+ */
+ new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
if (new)
return new;
@@ -115,18 +121,24 @@ static struct idr_layer *idr_layer_alloc
* Try to fetch one from the per-cpu preload buffer if in process
* context. See idr_preload() for details.
*/
- if (in_interrupt())
- return NULL;
-
- preempt_disable();
- new = __this_cpu_read(idr_preload_head);
- if (new) {
- __this_cpu_write(idr_preload_head, new->ary[0]);
- __this_cpu_dec(idr_preload_cnt);
- new->ary[0] = NULL;
+ if (!in_interrupt()) {
+ preempt_disable();
+ new = __this_cpu_read(idr_preload_head);
+ if (new) {
+ __this_cpu_write(idr_preload_head, new->ary[0]);
+ __this_cpu_dec(idr_preload_cnt);
+ new->ary[0] = NULL;
+ }
+ preempt_enable();
+ if (new)
+ return new;
}
- preempt_enable();
- return new;
+
+ /*
+ * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
+ * that memory allocation failure warning is printed as intended.
+ */
+ return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
}
static void idr_layer_rcu_free(struct rcu_head *head)
_
Patches currently in -mm which might be from tj@xxxxxxxxxx are
linux-next.patch
include-linux-res_counterh-needs-errnoh.patch
nfsd-remove-unused-get_new_stid.patch
nfsd-convert-to-idr_alloc.patch
workqueue-convert-to-idr_alloc.patch
mlx4-remove-leftover-idr_pre_get-call.patch
zcache-convert-to-idr_alloc.patch
tidspbridge-convert-to-idr_alloc.patch
idr-deprecate-idr_pre_get-and-idr_get_new.patch
idr-idr_alloc-shouldnt-trigger-lowmem-warning-when-preloaded.patch
thinkpad-acpi-kill-hotkey_thread_mutex.patch
block-restore-proc-partitions-to-not-display-non-partitionable-removable-devices.patch
memblock-add-assertion-for-zero-allocation-alignment.patch
rtc-add-devm_rtc_device_registerunregister.patch
rtc-use-struct-device-as-the-first-argument-for-devm_rtc_device_register.patch
kernel-sysc-use-the-simpler-call_usermodehelper.patch
usermodehelper-export-_exec-and-_setup-functions.patch
kmod-split-call-to-call_usermodehelper_fns.patch
keys-split-call-to-call_usermodehelper_fns.patch
coredump-remove-trailling-whitespaces.patch
split-remaining-calls-to-call_usermodehelper_fns.patch
kmod-remove-call_usermodehelper_fns.patch
coredump-only-sigkill-should-interrupt-the-coredumping-task.patch
coredump-ensure-that-sigkill-always-kills-the-dumping-thread.patch
coredump-sanitize-the-setting-of-signal-group_exit_code.patch
coredump-introduce-dump_interrupted.patch
coredump-factor-out-the-setting-of-pf_dumpcore.patch
coredump-change-wait_for_dump_helpers-to-use-wait_event_interruptible.patch
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