From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e3.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id lA1Jr1aP024764 for ; Thu, 1 Nov 2007 15:53:01 -0400 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v8.5) with ESMTP id lA1Jr1ok467078 for ; Thu, 1 Nov 2007 15:53:01 -0400 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id lA1Jr0ZL004548 for ; Thu, 1 Nov 2007 15:53:01 -0400 Subject: Re: [RFC][PATCH 1/3] [RFC][PATCH] Fix procfs task exe symlinks From: Matt Helsley In-Reply-To: <20071101122509.f26225bb.akpm@linux-foundation.org> References: <20071101033508.720885000@us.ibm.com> <20071101044124.209949000@us.ibm.com> <20071101122509.f26225bb.akpm@linux-foundation.org> Content-Type: text/plain Date: Thu, 01 Nov 2007 12:52:56 -0700 Message-Id: <1193946776.16995.5.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@ftp.linux.org.uk, haveblue@us.ibm.com List-ID: On Thu, 2007-11-01 at 12:25 -0700, Andrew Morton wrote: > On Wed, 31 Oct 2007 20:35:09 -0700 > Matt Helsley wrote: > > > +++ linux-2.6.23/include/linux/sched.h > > @@ -430,10 +430,13 @@ struct mm_struct { > > struct completion *core_startup_done, core_done; > > > > /* aio bits */ > > rwlock_t ioctx_list_lock; > > struct kioctx *ioctx_list; > > + > > + /* store ref to file /proc//exe symlink points to */ > > + struct file *exe_file; > > }; > > I guess with a little work this could be made conditional on > CONFIG_PROC_FS. ie: change get_mm_exe_file() to Sorry, I thought ifdefs were generally frowned upon in structs. I'll add them here and make sure everthing still works properly. > void get_mm_exe_file(struct mm_struct *newmm, struct mm_struct *old_mm); > > > @@ -1716,10 +1744,14 @@ static void remove_vma_list(struct mm_st > > > > mm->total_vm -= nrpages; > > if (vma->vm_flags & VM_LOCKED) > > mm->locked_vm -= nrpages; > > vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); > > + if (mm->exe_file && (vma->vm_file == mm->exe_file)) { > > + fput(mm->exe_file); > > + mm->exe_file = NULL; > > + } > > vma = remove_vma(vma); > > } while (vma); > > validate_mm(mm); > > } > > hm, fput() while holding mmap_sem. I wonder if that's a problem. > > I assume you've runtime tested this with lockdep enabled, but fput() is one > of those funny things which can call all sorts of things which one least > expects and where testers hit things which developers don't. It's being used under the mmap semaphore in remove_vma() so, even if fput() with mmap_sem held is a bug, I'm not introducing any new bugs :). Thanks, -Matt Helsley -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org