Message-Id: <93c9b84d6ec76aaf7b4f03468e22433a6d308674.1638267035.git.christophe.leroy@csgroup.eu>
Date:   Tue, 30 Nov 2021 11:10:43 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Erhard Furtner <erhard_f@...lbox.org>
Subject: [PATCH] powerpc/modules: Don't WARN on first module allocation tentative

module_alloc() first tries to allocate module text within
24 bits direct jump from kernel text, and tries a wider
allocation if first one fails.

When first allocation fails the following is observed in kernel logs:

vmap allocation for size 2400256 failed: use vmalloc=<size> to increase size
systemd-udevd: vmalloc error: size 2395133, vm_struct allocation failed, mode:0xcc0(GFP_KERNEL), nodemask=(null)
CPU: 0 PID: 127 Comm: systemd-udevd Tainted: G        W         5.15.5-gentoo-PowerMacG4 #9
Call Trace:
[e2a53a50] [c0ba0048] dump_stack_lvl+0x80/0xb0 (unreliable)
[e2a53a70] [c0540128] warn_alloc+0x11c/0x2b4
[e2a53b50] [c0531be8] __vmalloc_node_range+0xd8/0x64c
[e2a53c10] [c00338c0] module_alloc+0xa0/0xac
[e2a53c40] [c027a368] load_module+0x2ae0/0x8148
[e2a53e30] [c027fc78] sys_finit_module+0xfc/0x130
[e2a53f30] [c0035098] ret_from_syscall+0x0/0x28
--- interrupt: c00 at 0x25df10
NIP:  0025df10 LR: 00416180 CTR: 00000000
REGS: e2a53f40 TRAP: 0c00   Tainted: G        W          (5.15.5-gentoo-PowerMacG4)
MSR:  0000d032 <EE,PR,ME,IR,DR,RI>  CR: 2822242c  XER: 20000000

GPR00: 00000161 afa8f060 a73a6160 00000011 0041dfa5 00000000 00000011 00000000
GPR08: 00000000 20000000 0000007a afa8efe0 002113f8 0072f924 00000000 00000000
GPR16: 00000005 afa8f1fc afa8f1e8 00000000 22222422 00000000 009603b0 22222422
GPR24: 00000000 00000000 0041dfa5 008a5fc0 00020000 00000000 00444cc4 009958f0
NIP [0025df10] 0x25df10
LR [00416180] 0x416180
--- interrupt: c00
Mem-Info:
active_anon:36 inactive_anon:4417 isolated_anon:0
 active_file:3496 inactive_file:10535 isolated_file:0
 unevictable:0 dirty:59 writeback:0
 slab_reclaimable:3672 slab_unreclaimable:20540
 mapped:5700 shmem:166 pagetables:185 bounce:0
 kernel_misc_reclaimable:0
 free:438282 free_pcp:1121 free_cma:0
Node 0 active_anon:144kB inactive_anon:17668kB active_file:13984kB inactive_file:42140kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:22800kB dirty:404kB writeback:0kB shmem:664kB writeback_tmp:0kB kernel_stack:1352kB pagetables:740kB all_unreclaimable? no
DMA free:267900kB min:2488kB low:3108kB high:3728kB reserved_highatomic:4096KB active_anon:0kB inactive_anon:0kB active_file:4016kB inactive_file:4224kB unevictable:0kB writepending:76kB present:524288kB managed:389432kB mlocked:0kB bounce:0kB free_pcp:2480kB local_pcp:1176kB free_cma:0kB
lowmem_reserve[]: 0 0 1536 1536
HighMem free:1485036kB min:512kB low:3032kB high:5552kB reserved_highatomic:0KB active_anon:136kB inactive_anon:17612kB active_file:9976kB inactive_file:37912kB unevictable:0kB writepending:364kB present:1572864kB managed:1572864kB mlocked:0kB bounce:0kB free_pcp:1776kB local_pcp:404kB free_cma:0kB
BTRFS: selftest: sectorsize: 4096  nodesize: 8192
lowmem_reserve[]: 0 0 0 0
BTRFS: selftest: running btrfs free space cache tests
DMA: 283*4kB (UMH) 282*8kB (UMH) 242*16kB (UMEH) 422*32kB (UMH) 187*64kB (UMH) 139*128kB (UME) 118*256kB (UM) 87*512kB (UME) 61*1024kB (UME) 27*2048kB (U) 6*4096kB (U) = 267612kB
BTRFS: selftest: running extent only tests
HighMem: 1*4kB (M) 1*8kB (M) 92*16kB (M) 43*32kB (UM) 21*64kB (M) 7*128kB (M) 3*256kB (UM) 1*512kB (U) 2*1024kB (UM) 1*2048kB (U) 360*4096kB (UM) = 1485036kB
BTRFS: selftest: running bitmap only tests
14218 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap  = 8388604kB
Total swap = 8388604kB
524288 pages RAM
393216 pages HighMem/MovableOnly
33714 pages reserved

Add __GFP_NOWARN flag to first allocation so that no warning appears
when it fails.

Reported-by: Erhard Furtner <erhard_f@...lbox.org>
Fixes: 2ec13df16704 ("powerpc/modules: Load modules closer to kernel text")
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/module.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index ed04a3ba66fe..40a583e9d3c7 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -90,16 +90,17 @@ int module_finalize(const Elf_Ehdr *hdr,
 }
 
 static __always_inline void *
-__module_alloc(unsigned long size, unsigned long start, unsigned long end)
+__module_alloc(unsigned long size, unsigned long start, unsigned long end, bool nowarn)
 {
 	pgprot_t prot = strict_module_rwx_enabled() ? PAGE_KERNEL : PAGE_KERNEL_EXEC;
+	gfp_t gfp = GFP_KERNEL | (nowarn ? __GFP_NOWARN : 0);
 
 	/*
 	 * Don't do huge page allocations for modules yet until more testing
 	 * is done. STRICT_MODULE_RWX may require extra work to support this
 	 * too.
 	 */
-	return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, prot,
+	return __vmalloc_node_range(size, 1, start, end, gfp, prot,
 				    VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,
 				    NUMA_NO_NODE, __builtin_return_address(0));
 }
@@ -114,13 +115,13 @@ void *module_alloc(unsigned long size)
 
 	/* First try within 32M limit from _etext to avoid branch trampolines */
 	if (MODULES_VADDR < PAGE_OFFSET && MODULES_END > limit)
-		ptr = __module_alloc(size, limit, MODULES_END);
+		ptr = __module_alloc(size, limit, MODULES_END, true);
 
 	if (!ptr)
-		ptr = __module_alloc(size, MODULES_VADDR, MODULES_END);
+		ptr = __module_alloc(size, MODULES_VADDR, MODULES_END, false);
 
 	return ptr;
 #else
-	return __module_alloc(size, VMALLOC_START, VMALLOC_END);
+	return __module_alloc(size, VMALLOC_START, VMALLOC_END, false);
 #endif
 }
-- 
2.33.1

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