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selinux: use __GFP_NOWARN with GFP_NOWAIT in the AVC
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In the field, we have seen lots of allocation failure from the call
path below.

06-03 13:29:12.999 1010315 31557 31557 W Binder  : 31542_2: page allocation failure: order:0, mode:0x800(GFP_NOWAIT), nodemask=(null),cpuset=background,mems_allowed=0
...
...
06-03 13:29:12.999 1010315 31557 31557 W Call trace:
06-03 13:29:12.999 1010315 31557 31557 W         : dump_backtrace.cfi_jt+0x0/0x8
06-03 13:29:12.999 1010315 31557 31557 W         : dump_stack+0xc8/0x14c
06-03 13:29:12.999 1010315 31557 31557 W         : warn_alloc+0x158/0x1c8
06-03 13:29:12.999 1010315 31557 31557 W         : __alloc_pages_slowpath+0x9d8/0xb80
06-03 13:29:12.999 1010315 31557 31557 W         : __alloc_pages_nodemask+0x1c4/0x430
06-03 13:29:12.999 1010315 31557 31557 W         : allocate_slab+0xb4/0x390
06-03 13:29:12.999 1010315 31557 31557 W         : ___slab_alloc+0x12c/0x3a4
06-03 13:29:12.999 1010315 31557 31557 W         : kmem_cache_alloc+0x358/0x5e4
06-03 13:29:12.999 1010315 31557 31557 W         : avc_alloc_node+0x30/0x184
06-03 13:29:12.999 1010315 31557 31557 W         : avc_update_node+0x54/0x4f0
06-03 13:29:12.999 1010315 31557 31557 W         : avc_has_extended_perms+0x1a4/0x460
06-03 13:29:12.999 1010315 31557 31557 W         : selinux_file_ioctl+0x320/0x3d0
06-03 13:29:12.999 1010315 31557 31557 W         : __arm64_sys_ioctl+0xec/0x1fc
06-03 13:29:12.999 1010315 31557 31557 W         : el0_svc_common+0xc0/0x24c
06-03 13:29:12.999 1010315 31557 31557 W         : el0_svc+0x28/0x88
06-03 13:29:12.999 1010315 31557 31557 W         : el0_sync_handler+0x8c/0xf0
06-03 13:29:12.999 1010315 31557 31557 W         : el0_sync+0x1a4/0x1c0
..
..
06-03 13:29:12.999 1010315 31557 31557 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010315 31557 31557 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010315 31557 31557 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:12.999 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:12.999 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:12.999 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:12.999 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:12.999 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 1010161 10686 10686 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 1010161 10686 10686 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 1010161 10686 10686 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 10230 30892 30892 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 10230 30892 30892 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0
06-03 13:29:13.000 10230 30892 30892 W node 0  : slabs: 57, objs: 2907, free: 0
06-03 13:29:13.000 10230 30892 30892 W SLUB    : Unable to allocate memory on node -1, gfp=0x900(GFP_NOWAIT|__GFP_ZERO)
06-03 13:29:13.000 10230 30892 30892 W cache   : avc_node, object size: 72, buffer size: 80, default order: 0, min order: 0

Based on [1], selinux is tolerate for failure of memory allocation.
Then, use __GFP_NOWARN together.

[1] 476accb ("selinux: use GFP_NOWAIT in the AVC kmem_caches")

Signed-off-by: Minchan Kim <[email protected]>
[PM: subj fix, line wraps, normalized commit refs]
Signed-off-by: Paul Moore <[email protected]>
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@minchank @pcmoore
minchank authored and pcmoore committed Jun 11, 2021
1 parent 869cbee commit 648f2c6
Showing 1 changed file with 7 additions and 6 deletions.
13 changes: 7 additions & 6 deletions security/selinux/avc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -297,26 +297,27 @@ static struct avc_xperms_decision_node
struct avc_xperms_decision_node *xpd_node;
struct extended_perms_decision *xpd;

xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep, GFP_NOWAIT);
xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
GFP_NOWAIT | __GFP_NOWARN);
if (!xpd_node)
return NULL;

xpd = &xpd_node->xpd;
if (which & XPERMS_ALLOWED) {
xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
GFP_NOWAIT);
GFP_NOWAIT | __GFP_NOWARN);
if (!xpd->allowed)
goto error;
}
if (which & XPERMS_AUDITALLOW) {
xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
GFP_NOWAIT);
GFP_NOWAIT | __GFP_NOWARN);
if (!xpd->auditallow)
goto error;
}
if (which & XPERMS_DONTAUDIT) {
xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
GFP_NOWAIT);
GFP_NOWAIT | __GFP_NOWARN);
if (!xpd->dontaudit)
goto error;
}
Expand Down Expand Up @@ -344,7 +345,7 @@ static struct avc_xperms_node *avc_xperms_alloc(void)
{
struct avc_xperms_node *xp_node;

xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT);
xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
if (!xp_node)
return xp_node;
INIT_LIST_HEAD(&xp_node->xpd_head);
Expand Down Expand Up @@ -500,7 +501,7 @@ static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
{
struct avc_node *node;

node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT);
node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
if (!node)
goto out;

Expand Down

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