Segfault with error_page

[splitice]

Backtrace:

#0  0x080f2ac7 in ngx_http_syslog_error_handler (log=0x8cf4608,
    p=0xbfbae8b8 "\b\353\272\277L<\265\b\346", p_len=1960)
    at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:489
489         ngx_http_syslog_common_handler(
(gdb) backtrace full
#0  0x080f2ac7 in ngx_http_syslog_error_handler (log=0x8cf4608,
    p=0xbfbae8b8 "\b\353\272\277L<\265\b\346", p_len=1960)
    at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:489
No locals.
#1  0x080f2aea in ngx_http_syslog_error_handler (log=0x0, p=0xa <Address 0xa out of bounds>,
    p_len=3206221928) at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:494
No locals.
#2  0x080f2aea in ngx_http_syslog_error_handler (log=0xb7bc7380, p=0xb7bc6ff4 "|-\024",
    p_len=3206222780) at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:494
No locals.
#3  0x00000000 in ?? ()

Occurs when error_page is used, tested on a 504 error with config similar to:

@e504 {
    proxy_pass ...;
}

error_page 504 @e504;

nginx version: nginx/1.3.11

[splitice]

after a bit of debugging, I beleive the error occurs when an error is thrown within the named location.

Such as file not found, or any proxy_pass connection error. e.g if you use "location @test {
proxy_pass http://10.0.0.1;
}"
presuming 10.0.0.1 doesnt exist on your network.

[splitice]

and another backtrace generated that looks a bit different.

[splitice]

#0 0x080f2b18 in ngx_http_syslog_common_handler (source=2, level=6,
buf=0x8c9d480 "{ibootleg.org:46.17.96.109} ibootleg.org 79.161.51.12 - - [30/Jan/2013:08:25:44 +0400] "GET /search/valkyria%20chronicles%202 HTTP/1.0" 504 250 "-" "Mozilla/5.0 (compatible; MJ12bot/v1.4.3; http://www"..., len=229)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:510
conf = 0x8c9d565
ctx = 0x8e22b0c
map = 0xfe
i = 23
#1 0x080f27dd in ngx_http_syslog_log_request_handler (r=0x8dafba8)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:381
line = 0x8c9d480 "{ibootleg.org:46.17.96.109} ibootleg.org 79.161.51.12 - - [30/Jan/2013:08:25:44 +0400] "GET /search/valkyria%20chronicles%202 HTTP/1.0" 504 250 "-" "Mozilla/5.0 (compatible; MJ12bot/v1.4.3; http://www"...
len = 229
i = 2
l = 5
log = 0x1
lcf = 0x8d80860
conf = 0x8d80b8c
map = 0x8d80c1c
fmt = 0x8d6e96c
#2 0x0808e211 in ngx_http_log_request (r=0x8dafba8) at src/http/ngx_http_request.c:3276
i = 1
n = 2
log_handler = 0x8dde11c
cmcf = 0x8d6e644
#3 0x0808e0b9 in ngx_http_free_request (r=0x8dafba8, rc=0)
at src/http/ngx_http_request.c:3229
log = 0x8cefcd8
pool = 0xb7bae3a0
linger = {l_onoff = -1212488768, l_linger = 8}
cln = 0x0
ctx = 0xbf8959b8
clcf = 0xb7ad9d8c
#4 0x0808dfa4 in ngx_http_close_request (r=0x8dafba8, rc=0)
at src/http/ngx_http_request.c:3181
c = 0xb26ed138
#5 0x0808dcb6 in ngx_http_lingering_close_handler (rev=0x8e295c0)
at src/http/ngx_http_request.c:3048
n = 0
timer = 30
c = 0xb26ed138
r = 0x8dafba8
clcf = 0x1388
buffer = "F\251\276\267\250\002\317\b\210\003\317\b\000\000\000\000\070\251\277\267\250\002\317\b8\251\277\267XZ\211\277\250\252\276\267\210x\314\b\f\000\000\000\210x\314\bd,\322\267(\362\311\b\300\336\310\b\300\303\306\b\f\000\000\000(\362\311\b\300\336\310\b\254Q\337\b8\251\277\267\210\365\316\b\300\303\306\b\230Z\211\277y\361\276\267\300\303\306\b\000\000\000\000\210x\314\bQ\255\251\267\002\000\211\277\340X\367\267&\210\274\267\250\002\317\b\200\303\306\b\300\336\310\bP\363\311\b8\251\277\267\000\000\000\000\360\327\330\b8[\211\277\066\267\276\267\210\365\316\b\300\303\306\b\360\327\330\bH\242\314\b(\362\311\b\310\247\314\b8[\211\277\002\337\307\267\000\000\000\000\n\000\000\000\350Z\211\277/\247\251\267\000\257\277\267p\330\330\b\300\303\306\b\000\000\000\000\000\000\000\000\250\002\317\b\000\000\000\000\300\303\306\b\000\000\000\0
00\000\000\000\000\250\002\317\b", '\000' <repeats 12 times>"\360, \327\330\b\210\365\316\bH\000\000\000\270\343\272\267\071\000\000\000\000\000\000\000\240\343\272\267\364\317\272\267\240\343\272\267\070\251\277\267\210\365\316\b\360\327\330\b\310[\211\277b\312\276\267\360\327\330\b\200\246\314\b\001\000\000\000\270r\314\b(\362\311\b", '\000' <repeats 20 times>"\253, \347\306\267\070\251\277\267\210\365\316\b`\324\330\b\026f\255\267\062T\275\267", '\000' <repeats 12 times>"\210, \365\316\b\030)\277\267xv\277\267\300\303\306\b\000\000\000\000\000\000\000\000"...
#6 0x0806bb0f in ngx_event_process_posted (cycle=0x8d4cad8, posted=0x810fb7c)
at src/event/ngx_event_posted.c:40
ev = 0x8e295c0
#7 0x0806a22b in ngx_process_events_and_timers (cycle=0x8d4cad8) at src/event/ngx_event.c:276
flags = 3
timer = 5000
delta = 40
#8 0x08073889 in ngx_worker_process_cycle (cycle=0x8d4cad8, data=0x0)
at src/os/unix/ngx_process_cycle.c:807
worker = 0
i = 0
c = 0xbf896aa8
#9 0x08070f37 in ngx_spawn_process (cycle=0x8d4cad8,
proc=0x807376e <ngx_worker_process_cycle>, data=0x0, name=0x80f7408 "worker process",
respawn=-4) at src/os/unix/ngx_process.c:198
on = 1
pid = 0
s = 3
#10 0x08072d9c in ngx_start_worker_processes (cycle=0x8d4cad8, n=2, type=-4)
at src/os/unix/ngx_process_cycle.c:362
i = 0
ch = {command = 1, pid = 148164076, slot = 147169076, fd = 135288024}
#11 0x080729e3 in ngx_master_process_cycle (cycle=0x8d4cad8)
at src/os/unix/ngx_process_cycle.c:249
title = 0x8d58288 "master process /usr/sbin/nginx"
p = 0x8d582a6 ""
size = 31
i = 1
n = 0
sigio = 0
set = {__val = {0 <repeats 32 times>}}
itv = {it_interval = {tv_sec = -1208631004, tv_usec = 134681366}, it_value = {
tv_sec = 13, tv_usec = -1081513056}}
live = 1
delay = 0
ls = 0x6
ccf = 0x8d4cdec
#12 0x0804d847 in main (argc=1, argv=0xbf896df4) at src/core/nginx.c:412
i = 57
log = 0x810d894
cycle = 0x8c596f8
init_cycle = {conf_ctx = 0x0, pool = 0x8c590b0, log = 0x810d894, new_log = {
log_level = 0, file = 0x0, connection = 0, handler = 0, data = 0x0,
action = 0x0}, files = 0x0, free_connections = 0x0, free_connection_n = 0,
reusable_connections_queue = {prev = 0x0, next = 0x0}, listening = {elts = 0x0,
nelts = 0, size = 0, nalloc = 0, pool = 0x0}, paths = {elts = 0x0, nelts = 0,
size = 0, nalloc = 0, pool = 0x0}, open_files = {last = 0x0, part = {elts = 0x0,
nelts = 0, next = 0x0}, size = 0, nalloc = 0, pool = 0x0}, shared_memory = {
last = 0x0, part = {elts = 0x0, nelts = 0, next = 0x0}, size = 0, nalloc = 0,
pool = 0x0}, connection_n = 0, files_n = 0, connections = 0x0, read_events = 0x0,
write_events = 0x0, old_cycle = 0x0, conf_file = {len = 21,
data = 0x80f46f2 "/etc/nginx/nginx.conf"}, conf_param = {len = 0, data = 0x0},
conf_prefix = {len = 11, data = 0x80f46f2 "/etc/nginx/nginx.conf"}, prefix = {
len = 5, data = 0x80f46ec "/usr/"}, lock_file = {len = 0, data = 0x0},
hostname = {len = 0, data = 0x0}}
ccf = 0x8c59f34

[seletskiy]

Thx for bug report.

Can you attach minimal nginx.conf which reproduces bug, please? I can't reproduce bug just using named locations and error_page directive.

I found some wrong code related with this issue (which I'm fixing for now), but it does not segfaults nginx.

[splitice]

Sure stripping down my testing config now for you.

[splitice]

upstream does_not_exist {
        server 10.1.77.99;
}
server {
        #just to make timeout quicker
        proxy_read_timeout 2s;
        proxy_connect_timeout 2s;

        listen 88;

        location @e504 {
                internal;
                proxy_pass http://does_not_exist;
        }
        location / {
                root /does_not_exists/;
        }
        error_page 404 @e504;
}

That should do it.

[splitice]

If you require further assistance Ill give you access to a local testing server.

[seletskiy]

I think I fix a bug. If it does not work for you, let me know.

[splitice]

This issue appears to be fixed :) Ill deploy it on a live server tomorrow to confirm but its working fine on my testing server.

[splitice]

#69 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#70 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
---Type to continue, or q to quit---
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#71 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#72 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#73 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#74 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#75 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#76 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
---Type to continue, or q to quit---
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#77 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#78 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#79 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#80 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#81 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
---Type to continue, or q to quit---
#82 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#83 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#84 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#85 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#86 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#87 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
---Type to continue, or q to quit---
No locals.
#88 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#89 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#90 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#91 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#92 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#93 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
---Type to continue, or q to quit---
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#94 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#95 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#96 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#97 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#98 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#99 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
---Type to continue, or q to quit---
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#100 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#101 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#102 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#103 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#104 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
---Type to continue, or q to quit---
#105 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#106 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#107 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#108 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#109 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#110 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
---Type to continue, or q to quit---
No locals.
#111 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#112 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#113 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#114 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#115 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#116 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
---Type to continue, or q to quit---
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#117 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#118 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#119 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#120 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
No locals.
#121 0x080c1879 in ngx_http_syslog_error_handler (log=0x9a18cf8,
p=0xbfd0bea0 "\343\305\266\t", p_len=1920)
at /var/x4b/nginx-syslog-module/ngx_http_syslog_module.c:501
....

[seletskiy]

Do you have error_page directive in your production server?

[splitice]

Yes, the only difference between the two servers is that its proxy_pass call actually works, and that it gets a lot of traffic.

Im currently pushing out a temporary hack fix of

"""
if(r->connection->log->handler != ngx_http_syslog_error_handler)
ngx_http_syslog_ctx->old_handler = r->connection->log->handler;
"""

That I think should work temporarily as it does on my testing server, im pushing it to a production server now to confirm.

The config on the production server is something along the lines of
"""
location / {
proxy_pass http://10.0.92.118;
}
location @e504 {
#proxy cache is here but shouldnt matter
rewrite ^ /client/timeout.html break;
proxy_pass http://5.9.192.118;
}
error_page 504 @e504
"""

That should probably replicate it, I dont have a version without my modification compiled to confirm atm.

EDIT: Crappy hack of a patch by me does seem to work for now as far as I can tell.

[splitice]

Something that might be related now that I think of it, my production server has multiple http blocks with their own full configurations (error_page, logging etc)

e.g

http {
#sites doing XYZ
}
http {
#sites doing ABC
}

maybe that is causing double initialization?