svn commit: r326758 - in head/sys/i386: conf include

[Eugene Grosbein]

On 13.12.2017 04:55, John Baldwin wrote:
> On 12/12/17 3:09 PM, Eugene Grosbein wrote:
>> On 13.12.2017 02:32, John Baldwin wrote:
>>
>>> Certainly for MIPS I have found that compiling with clang
>>> instead of gcc for mips64 gives a kernel that panics for stack overflow for any
>>> use of NFS.  It might be that this is due to something MIPS-specific, but it
>>> might be worthwhile retesting with kstack_pages=2 and building the kernel
>>> with CROSS_TOOLCHAIN=i386-gcc after installing the appropriate package.
>>
>> You may want to check NFS code that uses stack heavily.
>> Here are numbers for i386 (bytes-on-stack, module, what function):
>>
>> 1344 nfs_nfsdport.o <nfssvc_nfsd>:
>> 1152 nfs_nfsdserv.o <nfsrvd_lockt>:
>> 1128 nfs_nfsdserv.o <nfsrvd_lock>:
>> 952 nfs_nfsdserv.o <nfsrvd_rename>:
>> 664 nfs_nfsdserv.o <nfsrvd_open>:
>> 640 nfs_nfsdserv.o <nfsrvd_link>:
>> 624 nfs_nfsdserv.o <nfsrvd_create>:
>> 608 nfs_nfsdserv.o <nfsrvd_mknod>:
>> 600 nfs_clvfsops.o <nfs_mount>:
> 
> My point is that you should compare gcc with clang as 10.x switched to
> clang and that may be a factor in the stack overflows beginning with 10.x.

I think thats's NFS code who is guilty. You can see example of amd64 (sic!) kstack exhaustion
due to 40+ frames deep call chain here:

https://lists.freebsd.org/pipermail/freebsd-stable/2017-July/087429.html