Date: Thu, 12 Dec 2024 17:46:40 +0800 From: Zhenlei Huang <zlei@FreeBSD.org> To: Rick Macklem <rick.macklem@gmail.com> Cc: FreeBSD CURRENT <freebsd-current@freebsd.org> Subject: Re: Module variable initialization Message-ID: <3FBDFCF4-4427-4653-9EE4-EBC44DCB72ED@FreeBSD.org> In-Reply-To: <CAM5tNy74ZC3FMTBWB1qj_LEhs_mv9ZXw-1SCs3rt=dLx1tkAKQ@mail.gmail.com> References: <CAM5tNy74ZC3FMTBWB1qj_LEhs_mv9ZXw-1SCs3rt=dLx1tkAKQ@mail.gmail.com>
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--Apple-Mail=_B2249E63-5891-4707-AE52-79A065BDA57A Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii > On Dec 12, 2024, at 10:44 AM, Rick Macklem <rick.macklem@gmail.com> = wrote: >=20 > Hi, >=20 > Bugzilla pr#282156 reports a crash that appears to be caused by > a NFS client variable (nfscbd_pool) not being initialized when a > NFS mount is done. >=20 > Now, the NFS client module (nfscl.ko) is weird in that it has > two definitions for the module. There is a VFS_SET() one for > the file system and a separate DECLARE_MODULE() for nfscl. > (The latter exists so that the module can refuse to unload and > define dependencies on other modules.) >=20 > The variable (nfscbd_pool) is initialized in the modevent() function > for nfscl in the MOD_LOAD section. >=20 > Does anyone know if this can somehow result in the variable not > being initialized when an NFS mount occurs? I'm not familiar with NFS. =46rom a quick look of the source code I = think `nfscbd_pool` is correctly initialized. I do not know the exact version pr#282156, so I guess and tried 14.1-p1, ``` $ addr2line -fip -e = /.zfs/snapshot/14.1-p1/usr/lib/debug/boot/kernel/kernel.debug = 0xffffffff80e1c558 svc_run at /usr/src/sys/rpc/svc.c:1414 ``` = https://cgit.freebsd.org/src/tree/sys/rpc/svc.c?h=3Dreleng/14.1&id=3D0892d= ff104440867956a53e78c12d66090fec36b#n1414 If `nfscbd_pool` is NULL, then I expect the panic should happens = earlier. Say line 1405 or event earlier line 1389 . Maybe `svc_run_internal()` is to be blamed ? >=20 > And, if the above is possible, would doing the initialization in the > vfs_init function for VFS_SET() be guaranteed to happen before > a mount is done? The order of modules seems right to me. nfscl module has order = SI_ORDER_FIRST and VFS_SET(... nfs ... ) has SI_ORDER_MIDDLE. >=20 > Thanks for any help with this, rick >=20 Best regards, Zhenlei --Apple-Mail=_B2249E63-5891-4707-AE52-79A065BDA57A Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii <html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; = charset=3Dus-ascii"></head><body style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><br = class=3D""><div><br class=3D""><blockquote type=3D"cite" class=3D""><div = class=3D"">On Dec 12, 2024, at 10:44 AM, Rick Macklem <<a = href=3D"mailto:rick.macklem@gmail.com" = class=3D"">rick.macklem@gmail.com</a>> wrote:</div><br = class=3D"Apple-interchange-newline"><div class=3D""><div class=3D"">Hi,<br= class=3D""><br class=3D"">Bugzilla pr#282156 reports a crash that = appears to be caused by<br class=3D"">a NFS client variable = (nfscbd_pool) not being initialized when a<br class=3D"">NFS mount is = done.<br class=3D""><br class=3D"">Now, the NFS client module (nfscl.ko) = is weird in that it has<br class=3D"">two definitions for the module. = There is a VFS_SET() one for<br class=3D"">the file system and a = separate DECLARE_MODULE() for nfscl.<br class=3D"">(The latter exists so = that the module can refuse to unload and<br class=3D"">define = dependencies on other modules.)<br class=3D""><br class=3D"">The = variable (nfscbd_pool) is initialized in the modevent() function<br = class=3D"">for nfscl in the MOD_LOAD = section.</div></div></blockquote><blockquote type=3D"cite" class=3D""><div= class=3D""><div class=3D""><br class=3D"">Does anyone know if this can = somehow result in the variable not<br class=3D"">being initialized when = an NFS mount occurs?<br class=3D""></div></div></blockquote><div><br = class=3D""></div><div><div style=3D"caret-color: rgb(0, 0, 0); color: = rgb(0, 0, 0);">I'm not familiar with NFS. =46rom a quick look of the = source code I think</div><div style=3D"caret-color: rgb(0, 0, 0); color: = rgb(0, 0, 0);">`nfscbd_pool` is correctly initialized.</div><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"><br = class=3D""></div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, = 0, 0);">I do not know the exact version pr#282156, so I guess and tried = 14.1-p1,</div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, = 0);">```</div><div><span style=3D"caret-color: rgb(0, 0, 0); color: = rgb(0, 0, 0);" class=3D"">$ </span><font color=3D"#000000" = class=3D""><span style=3D"caret-color: rgb(0, 0, 0);" class=3D"">addr2line= -fip -e /.zfs/snapshot/14.1-p1/usr/lib/debug/boot/kernel/kernel.debug = 0xffffffff80e1c558</span></font></div><div><font color=3D"#000000" = class=3D""><span style=3D"caret-color: rgb(0, 0, 0);" class=3D"">svc_run = at /usr/src/sys/rpc/svc.c:1414</span></font></div><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">```</div><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"><br = class=3D""></div><div><font color=3D"#000000" class=3D""><span = style=3D"caret-color: rgb(0, 0, 0);" class=3D""><a = href=3D"https://cgit.freebsd.org/src/tree/sys/rpc/svc.c?h=3Dreleng/14.1&am= p;id=3D0892dff104440867956a53e78c12d66090fec36b#n1414" = class=3D"">https://cgit.freebsd.org/src/tree/sys/rpc/svc.c?h=3Dreleng/14.1= &id=3D0892dff104440867956a53e78c12d66090fec36b#n1414</a></span></font>= </div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"><br = class=3D""></div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, = 0, 0);">If `nfscbd_pool` is NULL, then I expect the panic should happens = earlier. Say line 1405 or event earlier line 1389 .</div><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"><br = class=3D""></div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, = 0, 0);">Maybe `svc_run_internal()` is to be blamed ?</div></div><br = class=3D""><blockquote type=3D"cite" class=3D""><div class=3D""><div = class=3D""><br class=3D"">And, if the above is possible, would doing the = initialization in the<br class=3D"">vfs_init function for VFS_SET() be = guaranteed to happen before<br class=3D"">a mount is done?<br = class=3D""></div></div></blockquote><div><br class=3D""></div><div>The = order of modules seems right to me. nfscl module has order <span = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" = class=3D"">SI_ORDER_FIRST</span></div><div><span style=3D"caret-color: = rgb(0, 0, 0); color: rgb(0, 0, 0);" class=3D"">and </span><span = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" = class=3D"">VFS_SET(... nfs ... ) has </span><span = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);" = class=3D"">SI_ORDER_MIDDLE.</span></div><br class=3D""><blockquote = type=3D"cite" class=3D""><div class=3D""><div class=3D""><br = class=3D"">Thanks for any help with this, rick<br class=3D""><br = class=3D""></div></div></blockquote></div><br class=3D""><div class=3D""> <div>Best regards,</div><div>Zhenlei</div> </div> <br class=3D""></body></html>= --Apple-Mail=_B2249E63-5891-4707-AE52-79A065BDA57A--
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