Benjamin Herrenschmidt wrote:
No, Mel's patch is for a different problem and has been fixed upstream
already. This is more concerning... I'm not sure what's up but would
you be able to send a disassembly of the hpte_need_flush() function in
your kernel binary for me to see what access precisely caused the
fault ?
Was able to recreate this with git3 kernel. Here is the disassembly
shm-fork 10 10 (64): PASS
shm-fork 10 20 (32): cpu 0x1: Vector: 300 (Data Access) at [c0000000faa13490]
pc: c000000000038240: .hpte_need_flush+0x1bc/0x2d8
lr: c0000000000380f0: .hpte_need_flush+0x6c/0x2d8
sp: c0000000faa13710
msr: 8000000000009032
dar: c00000005e5e0480
dsisr: 40000000
current = 0xc0000000f9bde3e0
paca = 0xc000000000b72600
pid = 12152, comm = shm-fork
enter ? for help
[c0000000faa13710] c000000000038264 .hpte_need_flush+0x1e0/0x2d8 (unreliable)
[c0000000faa137d0] c000000000039fa4 .huge_ptep_get_and_clear+0x40/0x5c
[c0000000faa13850] c00000000012d044 .__unmap_hugepage_range+0x178/0x2b8
[c0000000faa13940] c00000000012d1d8 .unmap_hugepage_range+0x54/0x88
[c0000000faa139e0] c000000000116f78 .unmap_vmas+0x178/0x8f4
[c0000000faa13b30] c00000000011c690 .unmap_region+0xfc/0x1e4
[c0000000faa13c00] c00000000011de20 .do_munmap+0x2f4/0x38c
[c0000000faa13cc0] c0000000002f6a08 .SyS_shmdt+0xc0/0x188
[c0000000faa13d70] c00000000000c430 .sys_ipc+0x274/0x2fc
[c0000000faa13e30] c000000000008534 syscall_exit+0x0/0x40
--- Exception: c01 (System Call) at 000004000021d2dc
SP (fffee026010) is in userspace
1:mon> di $.hpte_need_flush
c000000000038084 fac1ffb0 std r22,-80(r1)
c000000000038088 7c0802a6 mflr r0
c00000000003808c f8010010 std r0,16(r1)
c000000000038090 2fa70000 cmpdi cr7,r7,0
c000000000038094 fb21ffc8 std r25,-56(r1)
c000000000038098 6cc01000 xoris r0,r6,4096
c00000000003809c fb41ffd0 std r26,-48(r1)
c0000000000380a0 7cd93378 mr r25,r6
c0000000000380a4 fb61ffd8 std r27,-40(r1)
c0000000000380a8 7cb62b78 mr r22,r5
c0000000000380ac fb81ffe0 std r28,-32(r1)
......... <SNIP> .........
1:mon>
c000000000038204 38090001 addi r0,r9,1
c000000000038208 78004602 rldicl r0,r0,40,24
c00000000003820c 7c004a14 add r0,r0,r9
c000000000038210 78090220 clrldi r9,r0,40
c000000000038214 2fbd0000 cmpdi cr7,r29,0
c000000000038218 409e0010 bne cr7,c000000000038228 #
.hpte_need_flush+0x1a4/0x2d8
c00000000003821c 7929e0e4 rldicr r9,r9,28,35
c000000000038220 7be00120 clrldi r0,r31,36
c000000000038224 4800000c b c000000000038230 #
.hpte_need_flush+0x1ac/0x2d8
c000000000038228 792945c6 rldicr r9,r9,40,23
c00000000003822c 7be00600 clrldi r0,r31,24
c000000000038230 7d3f0378 or r31,r9,r0
c000000000038234 7c1cb82e lwzx r0,r28,r23
c000000000038238 3d360001 addis r9,r22,1
c00000000003823c 2f800000 cmpwi cr7,r0,0
c000000000038240 eb898000 ld r28,-32768(r9) <<== +0x1bc should be
this
1:mon> r
R00 = 0000000000000000 R16 = 0000000023aa4db0
R01 = c0000000faa13710 R17 = 0000000000000000
R02 = c000000000a9d788 R18 = ffffffffffff9010
R03 = 0000000000000004 R19 = 0000000000000000
R04 = 000003fff0000000 R20 = 0000000000000000
R05 = c00000005e5d8480 R21 = 0000040000000000
R06 = 0000364008000393 R22 = c00000005e5d8480
R07 = 0000000000000001 R23 = 0000000000750000
R08 = 0000000000000004 R24 = 0000000000000000
R09 = c00000005e5e8480 R25 = 0000364008000393
R10 = 000000000003fff0 R26 = c0000000673f0680
R11 = 0000000000000280 R27 = 0000000000000004
R12 = 0000000044022422 R28 = c000000000890430
R13 = c000000000b72600 R29 = 0000000000000001
R14 = 00000000ffffffff R30 = c000000000fe0430
R15 = ffffffffffffffff R31 = 8812ebfff0000000
pc = c000000000038240 .hpte_need_flush+0x1bc/0x2d8
lr = c0000000000380f0 .hpte_need_flush+0x6c/0x2d8
msr = 8000000000009032 cr = 44022422
ctr = c00000000025cc28 xer = 0000000000000001 trap = 300
dar = c00000005e5e0480 dsisr = 40000000
1:mon>
Have attached the complete disassembly.
Thanks
-Sachin
--
---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
---------------------------------
shm-fork 10 10 (64): PASS
shm-fork 10 20 (32): cpu 0x1: Vector: 300 (Data Access) at [c0000000faa13490]
pc: c000000000038240: .hpte_need_flush+0x1bc/0x2d8
lr: c0000000000380f0: .hpte_need_flush+0x6c/0x2d8
sp: c0000000faa13710
msr: 8000000000009032
dar: c00000005e5e0480
dsisr: 40000000
current = 0xc0000000f9bde3e0
paca = 0xc000000000b72600
pid = 12152, comm = shm-fork
enter ? for help
[c0000000faa13710] c000000000038264 .hpte_need_flush+0x1e0/0x2d8 (unreliable)
[c0000000faa137d0] c000000000039fa4 .huge_ptep_get_and_clear+0x40/0x5c
[c0000000faa13850] c00000000012d044 .__unmap_hugepage_range+0x178/0x2b8
[c0000000faa13940] c00000000012d1d8 .unmap_hugepage_range+0x54/0x88
[c0000000faa139e0] c000000000116f78 .unmap_vmas+0x178/0x8f4
[c0000000faa13b30] c00000000011c690 .unmap_region+0xfc/0x1e4
[c0000000faa13c00] c00000000011de20 .do_munmap+0x2f4/0x38c
[c0000000faa13cc0] c0000000002f6a08 .SyS_shmdt+0xc0/0x188
[c0000000faa13d70] c00000000000c430 .sys_ipc+0x274/0x2fc
[c0000000faa13e30] c000000000008534 syscall_exit+0x0/0x40
--- Exception: c01 (System Call) at 000004000021d2dc
SP (fffee026010) is in userspace
1:mon> di $.hpte_need_flush
c000000000038084 fac1ffb0 std r22,-80(r1)
c000000000038088 7c0802a6 mflr r0
c00000000003808c f8010010 std r0,16(r1)
c000000000038090 2fa70000 cmpdi cr7,r7,0
c000000000038094 fb21ffc8 std r25,-56(r1)
c000000000038098 6cc01000 xoris r0,r6,4096
c00000000003809c fb41ffd0 std r26,-48(r1)
c0000000000380a0 7cd93378 mr r25,r6
c0000000000380a4 fb61ffd8 std r27,-40(r1)
c0000000000380a8 7cb62b78 mr r22,r5
c0000000000380ac fb81ffe0 std r28,-32(r1)
c0000000000380b0 eb828d30 ld r28,-29392(r2)
c0000000000380b4 fbc1fff0 std r30,-16(r1)
c0000000000380b8 781b27e2 rldicl r27,r0,36,63
c0000000000380bc fbe1fff8 std r31,-8(r1)
c0000000000380c0 7c7a1b78 mr r26,r3
1:mon>
c0000000000380c4 fae1ffb8 std r23,-72(r1)
c0000000000380c8 789f03e4 rldicr r31,r4,0,47
c0000000000380cc fb01ffc0 std r24,-64(r1)
c0000000000380d0 fba1ffe8 std r29,-24(r1)
c0000000000380d4 f821ff41 stdu r1,-192(r1)
c0000000000380d8 eaed0040 ld r23,64(r13)
c0000000000380dc 7fdcba14 add r30,r28,r23
c0000000000380e0 eb1e0008 ld r24,8(r30)
c0000000000380e4 419e0014 beq cr7,c0000000000380f8 # .hpte_need_flush+0x74/0x2d8
c0000000000380e8 7fe4fb78 mr r4,r31
c0000000000380ec 48000d85 bl c000000000038e70 # .get_slice_psize+0x0/0x38
c0000000000380f0 60000000 nop
c0000000000380f4 7c7b1b78 mr r27,r3
c0000000000380f8 e8028d38 ld r0,-29384(r2)
c0000000000380fc 7fbf0040 cmpld cr7,r31,r0
c000000000038100 419d00a8 bgt cr7,c0000000000381a8 # .hpte_need_flush+0x124/0x2d8
1:mon>
c000000000038104 3800ffff li r0,-1
c000000000038108 3ba00000 li r29,0
c00000000003810c 78000600 clrldi r0,r0,24
c000000000038110 7fbf0040 cmpld cr7,r31,r0
c000000000038114 409d000c ble cr7,c000000000038120 # .hpte_need_flush+0x9c/0x2d8
c000000000038118 e9228d40 ld r9,-29376(r2)
c00000000003811c eba90002 lwa r29,0(r9)
c000000000038120 2fbd0000 cmpdi cr7,r29,0
c000000000038124 e97a0390 ld r11,912(r26)
c000000000038128 409e003c bne cr7,c000000000038164 # .hpte_need_flush+0xe0/0x2d8
c00000000003812c 796b83e4 rldicr r11,r11,16,47
c000000000038130 7be02702 rldicl r0,r31,36,28
c000000000038134 3d200bf6 lis r9,3062
c000000000038138 7c005b78 or r0,r0,r11
c00000000003813c 6129e61b ori r9,r9,58907
c000000000038140 7c0049d2 mulld r0,r0,r9
1:mon>
c000000000038144 78090700 clrldi r9,r0,28
c000000000038148 7800e120 rldicl r0,r0,28,36
c00000000003814c 7d290214 add r9,r9,r0
c000000000038150 38090001 addi r0,r9,1
c000000000038154 7800e120 rldicl r0,r0,28,36
c000000000038158 7c004a14 add r0,r0,r9
c00000000003815c 78090700 clrldi r9,r0,28
c000000000038160 48000038 b c000000000038198 # .hpte_need_flush+0x114/0x2d8
c000000000038164 796b26e4 rldicr r11,r11,4,59
c000000000038168 7be0c220 rldicl r0,r31,24,40
c00000000003816c 3d2000bf lis r9,191
c000000000038170 7c005b78 or r0,r0,r11
c000000000038174 612950d9 ori r9,r9,20697
c000000000038178 7c0049d2 mulld r0,r0,r9
c00000000003817c 78090220 clrldi r9,r0,40
c000000000038180 78004602 rldicl r0,r0,40,24
1:mon>
c000000000038184 7d290214 add r9,r9,r0
c000000000038188 38090001 addi r0,r9,1
c00000000003818c 78004602 rldicl r0,r0,40,24
c000000000038190 7c004a14 add r0,r0,r9
c000000000038194 78090220 clrldi r9,r0,40
c000000000038198 7d200074 cntlzd r0,r9
c00000000003819c 7800d182 rldicl r0,r0,58,6
c0000000000381a0 0b000000 tdnei r0,0
c0000000000381a4 48000070 b c000000000038214 # .hpte_need_flush+0x190/0x2d8
c0000000000381a8 e9228d48 ld r9,-29368(r2)
c0000000000381ac eba90002 lwa r29,0(r9)
c0000000000381b0 2fbd0000 cmpdi cr7,r29,0
c0000000000381b4 409e0034 bne cr7,c0000000000381e8 # .hpte_need_flush+0x164/0x2d8
c0000000000381b8 3d200bf6 lis r9,3062
c0000000000381bc 7be02702 rldicl r0,r31,36,28
c0000000000381c0 6129e61b ori r9,r9,58907
1:mon>
c0000000000381c4 7c0049d2 mulld r0,r0,r9
c0000000000381c8 78090700 clrldi r9,r0,28
c0000000000381cc 7800e120 rldicl r0,r0,28,36
c0000000000381d0 7d290214 add r9,r9,r0
c0000000000381d4 38090001 addi r0,r9,1
c0000000000381d8 7800e120 rldicl r0,r0,28,36
c0000000000381dc 7c004a14 add r0,r0,r9
c0000000000381e0 78090700 clrldi r9,r0,28
c0000000000381e4 48000038 b c00000000003821c # .hpte_need_flush+0x198/0x2d8
c0000000000381e8 3d2000bf lis r9,191
c0000000000381ec 7be0c220 rldicl r0,r31,24,40
c0000000000381f0 612950d9 ori r9,r9,20697
c0000000000381f4 7c0049d2 mulld r0,r0,r9
c0000000000381f8 78090220 clrldi r9,r0,40
c0000000000381fc 78004602 rldicl r0,r0,40,24
c000000000038200 7d290214 add r9,r9,r0
1:mon>
c000000000038204 38090001 addi r0,r9,1
c000000000038208 78004602 rldicl r0,r0,40,24
c00000000003820c 7c004a14 add r0,r0,r9
c000000000038210 78090220 clrldi r9,r0,40
c000000000038214 2fbd0000 cmpdi cr7,r29,0
c000000000038218 409e0010 bne cr7,c000000000038228 # .hpte_need_flush+0x1a4/0x2d8
c00000000003821c 7929e0e4 rldicr r9,r9,28,35
c000000000038220 7be00120 clrldi r0,r31,36
c000000000038224 4800000c b c000000000038230 # .hpte_need_flush+0x1ac/0x2d8
c000000000038228 792945c6 rldicr r9,r9,40,23
c00000000003822c 7be00600 clrldi r0,r31,24
c000000000038230 7d3f0378 or r31,r9,r0
c000000000038234 7c1cb82e lwzx r0,r28,r23
c000000000038238 3d360001 addis r9,r22,1
c00000000003823c 2f800000 cmpwi cr7,r0,0
c000000000038240 eb898000 ld r28,-32768(r9)
1:mon> r
R00 = 0000000000000000 R16 = 0000000023aa4db0
R01 = c0000000faa13710 R17 = 0000000000000000
R02 = c000000000a9d788 R18 = ffffffffffff9010
R03 = 0000000000000004 R19 = 0000000000000000
R04 = 000003fff0000000 R20 = 0000000000000000
R05 = c00000005e5d8480 R21 = 0000040000000000
R06 = 0000364008000393 R22 = c00000005e5d8480
R07 = 0000000000000001 R23 = 0000000000750000
R08 = 0000000000000004 R24 = 0000000000000000
R09 = c00000005e5e8480 R25 = 0000364008000393
R10 = 000000000003fff0 R26 = c0000000673f0680
R11 = 0000000000000280 R27 = 0000000000000004
R12 = 0000000044022422 R28 = c000000000890430
R13 = c000000000b72600 R29 = 0000000000000001
R14 = 00000000ffffffff R30 = c000000000fe0430
R15 = ffffffffffffffff R31 = 8812ebfff0000000
pc = c000000000038240 .hpte_need_flush+0x1bc/0x2d8
lr = c0000000000380f0 .hpte_need_flush+0x6c/0x2d8
msr = 8000000000009032 cr = 44022422
ctr = c00000000025cc28 xer = 0000000000000001 trap = 300
dar = c00000005e5e0480 dsisr = 40000000
1:mon>
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