epoll broken [was: mmotm 2011-01-25-15-47 uploaded]

epoll broken [was: mmotm 2011-01-25-15-47 uploaded]

[Jiri Slaby]

On 01/26/2011 12:48 AM, akpm@linux-foundation.org wrote:
> The mm-of-the-moment snapshot 2011-01-25-15-47 has been uploaded to

Hi, the network daemons are broken here. cupsd and httpd children
segfault too often without servicing requests. It's a regression against
mmotm 2011-01-06-15-41.

It's epoll after it dies:
17836 epoll_create(8192)                = 3
...
17836 accept(7, {sa_family=AF_FILE, NULL}, [2]) = 11
17836 getsockname(11, {sa_family=AF_FILE,
path="/var/run/cups/cups.sock"}, [26]) = 0
17836 setsockopt(11, SOL_TCP, TCP_NODELAY, [1], 4) = -1 EOPNOTSUPP
(Operation not supported)
17836 fcntl(11, F_GETFD)                = 0
17836 fcntl(11, F_SETFD, FD_CLOEXEC)    = 0
17836 epoll_ctl(3, EPOLL_CTL_ADD, 11, {EPOLLIN, {u32=379708832,
u64=140428630418848}}) = 0
17836 epoll_wait(3, {{EPOLLIN, {u32=379708832, u64=140428630418848}}},
8192, 1000) = 1
17836 recvfrom(11, "P", 1, MSG_PEEK, NULL, NULL) = 1
17836 poll([{fd=11, events=POLLIN}], 1, 10000) = 1 ([{fd=11,
revents=POLLIN}])
17836 recvfrom(11, "POST / HTTP/1.1\r\nContent-Length:"..., 2048, 0,
NULL, NULL) = 771
17836 sendto(11, "HTTP/1.1 100 Continue\r\n\r\n", 25, 0, NULL, 0) = 25
17836 epoll_wait(3, {{EPOLLIN, {u32=379708832, u64=140428630418848}},
{0, {u32=0, u64=0}} .............. {0, {u32=0, u64=0}}, ?}
0x7fb816996660, 8192, 0) = 379151968
17836 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
17836 +++ killed by SIGSEGV +++

The parameter, the same as the retval, seems to be bogus.

Is it known (fixed in newer kernels)?

thanks,
-- 
js

Re: epoll broken [was: mmotm 2011-01-25-15-47 uploaded]

[Eric Dumazet]

Le jeudi 03 février 2011 à 08:39 +0100, Jiri Slaby a écrit :
> On 01/26/2011 12:48 AM, akpm@linux-foundation.org wrote:
> > The mm-of-the-moment snapshot 2011-01-25-15-47 has been uploaded to
> 
> Hi, the network daemons are broken here. cupsd and httpd children
> segfault too often without servicing requests. It's a regression against
> mmotm 2011-01-06-15-41.
> 
> It's epoll after it dies:
> 17836 epoll_create(8192)                = 3
> ...
> 17836 accept(7, {sa_family=AF_FILE, NULL}, [2]) = 11
> 17836 getsockname(11, {sa_family=AF_FILE,
> path="/var/run/cups/cups.sock"}, [26]) = 0
> 17836 setsockopt(11, SOL_TCP, TCP_NODELAY, [1], 4) = -1 EOPNOTSUPP
> (Operation not supported)
> 17836 fcntl(11, F_GETFD)                = 0
> 17836 fcntl(11, F_SETFD, FD_CLOEXEC)    = 0
> 17836 epoll_ctl(3, EPOLL_CTL_ADD, 11, {EPOLLIN, {u32=379708832,
> u64=140428630418848}}) = 0
> 17836 epoll_wait(3, {{EPOLLIN, {u32=379708832, u64=140428630418848}}},
> 8192, 1000) = 1
> 17836 recvfrom(11, "P", 1, MSG_PEEK, NULL, NULL) = 1
> 17836 poll([{fd=11, events=POLLIN}], 1, 10000) = 1 ([{fd=11,
> revents=POLLIN}])
> 17836 recvfrom(11, "POST / HTTP/1.1\r\nContent-Length:"..., 2048, 0,
> NULL, NULL) = 771
> 17836 sendto(11, "HTTP/1.1 100 Continue\r\n\r\n", 25, 0, NULL, 0) = 25
> 17836 epoll_wait(3, {{EPOLLIN, {u32=379708832, u64=140428630418848}},
> {0, {u32=0, u64=0}} .............. {0, {u32=0, u64=0}}, ?}
> 0x7fb816996660, 8192, 0) = 379151968
> 17836 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> 17836 +++ killed by SIGSEGV +++
> 
> The parameter, the same as the retval, seems to be bogus.
> 
> Is it known (fixed in newer kernels)?
> 
> thanks,

Yes, its known, and a fix is there : https://lkml.org/lkml/2011/1/26/121

Re: epoll broken [was: mmotm 2011-01-25-15-47 uploaded]

[Jiri Slaby]

On 02/03/2011 08:53 AM, Eric Dumazet wrote:
>> {0, {u32=0, u64=0}} .............. {0, {u32=0, u64=0}}, ?}
>> 0x7fb816996660, 8192, 0) = 379151968
>> 17836 --- SIGSEGV (Segmentation fault) @ 0 (0) ---
>> 17836 +++ killed by SIGSEGV +++
>>
>> The parameter, the same as the retval, seems to be bogus.
>>
>> Is it known (fixed in newer kernels)?
>>
>> thanks,
> 
> Yes, its known, and a fix is there : https://lkml.org/lkml/2011/1/26/121

Thanks, it works indeed.

-- 
js