From: Tharindu Rukshan Bamunuarachchi Subject: Re: TMPFS over NFSv4 Date: Tue, 25 May 2010 10:00:29 +0100 Message-ID: References: <20100524110903.72524853@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Cc: Greg KH , Alan Cox , linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@kernel.org To: Hugh Dickins Return-path: In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: hope that the 2.6.27.48 or later will be shipped with SP1 :-) __ tharindu.info "those that can, do. Those that can=92t, complain." -- Linus On Tue, May 25, 2010 at 12:46 AM, Hugh Dickins wrote: > Hi Greg, > > On Mon, 24 May 2010, Alan Cox wrote: >> On Mon, 24 May 2010 02:57:30 -0700 >> Hugh Dickins wrote: >> > On Mon, May 24, 2010 at 2:26 AM, Tharindu Rukshan Bamunuarachchi >> > wrote: >> > > thankx a lot Hugh ... I will try this out ... (bit harder patch >> > > already patched SLES kernel :-p ) .... >> > >> > If patch conflicts are a problem, you really only need to put in the >> > two-liner patch to mm/mmap.c: Alan was seeking perfection in >> > the rest of the patch, but you can get away without it. >> > >> > > >> > > BTW, what does Alan means by "strict overcommit" ? >> > >> > Ah, that phrase, yes, it's a nonsense, but many of us do say it by mis= take. >> > Alan meant to say "strict no-overcommit". >> >> No I always meant to say 'strict overcommit'. It avoids excess negatives >> and "no noovercommit" discussions. >> >> I guess 'strict overcommit control' would have been clearer 8) >> >> Alan > > I see we've just missed 2.6.27.47-rc1, but if there's to be an -rc2, > please include Alan's 2.6.28 oops fix below: which Tharindu appears > to be needing - just now discussed on linux-mm and linux-nfs. > Failing that, please queue it up for 2.6.27.48. > > Or if you'd prefer a smaller patch for -stable, then just the mm/mmap.c > part of it should suffice: I think it's fair to say that the rest of the > patch was more precautionary - as Alan describes, for catching other bugs= , > so good for an ongoing development tree, but not necessarily in -stable. > (However, Alan may disagree - I've already misrepresented him once here!) > > Thanks, > Hugh > > commit 731572d39fcd3498702eda4600db4c43d51e0b26 > Author: Alan Cox > Date: =A0 Wed Oct 29 14:01:20 2008 -0700 > > =A0 =A0nfsd: fix vm overcommit crash > > =A0 =A0Junjiro R. =A0Okajima reported a problem where knfsd crashes if yo= u are > =A0 =A0using it to export shmemfs objects and run strict overcommit. =A0I= n this > =A0 =A0situation the current->mm based modifier to the overcommit goes th= rough a > =A0 =A0NULL pointer. > > =A0 =A0We could simply check for NULL and skip the modifier but we've cau= ght > =A0 =A0other real bugs in the past from mm being NULL here - cases where = we did > =A0 =A0need a valid mm set up (eg the exec bug about a year ago). > > =A0 =A0To preserve the checks and get the logic we want shuffle the check= ing > =A0 =A0around and add a new helper to the vm_ security wrappers > > =A0 =A0Also fix a current->mm reference in nommu that should use the pass= ed mm > > =A0 =A0[akpm@linux-foundation.org: coding-style fixes] > =A0 =A0[akpm@linux-foundation.org: fix build] > =A0 =A0Reported-by: Junjiro R. Okajima > =A0 =A0Acked-by: James Morris > =A0 =A0Signed-off-by: Alan Cox > =A0 =A0Signed-off-by: Andrew Morton > =A0 =A0Signed-off-by: Linus Torvalds > > diff --git a/include/linux/security.h b/include/linux/security.h > index f5c4a51..c13f1ce 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1585,6 +1585,7 @@ int security_syslog(int type); > =A0int security_settime(struct timespec *ts, struct timezone *tz); > =A0int security_vm_enough_memory(long pages); > =A0int security_vm_enough_memory_mm(struct mm_struct *mm, long pages); > +int security_vm_enough_memory_kern(long pages); > =A0int security_bprm_alloc(struct linux_binprm *bprm); > =A0void security_bprm_free(struct linux_binprm *bprm); > =A0void security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe); > @@ -1820,6 +1821,11 @@ static inline int security_vm_enough_memory(long p= ages) > =A0 =A0 =A0 =A0return cap_vm_enough_memory(current->mm, pages); > =A0} > > +static inline int security_vm_enough_memory_kern(long pages) > +{ > + =A0 =A0 =A0 return cap_vm_enough_memory(current->mm, pages); > +} > + > =A0static inline int security_vm_enough_memory_mm(struct mm_struct *mm, l= ong pages) > =A0{ > =A0 =A0 =A0 =A0return cap_vm_enough_memory(mm, pages); > diff --git a/mm/mmap.c b/mm/mmap.c > index 74f4d15..de14ac2 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -175,7 +175,8 @@ int __vm_enough_memory(struct mm_struct *mm, long pag= es, int cap_sys_admin) > > =A0 =A0 =A0 =A0/* Don't let a single process grow too big: > =A0 =A0 =A0 =A0 =A0 leave 3% of the size of this process for other proces= ses */ > - =A0 =A0 =A0 allowed -=3D mm->total_vm / 32; > + =A0 =A0 =A0 if (mm) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 allowed -=3D mm->total_vm / 32; > > =A0 =A0 =A0 =A0/* > =A0 =A0 =A0 =A0 * cast `allowed' as a signed long because vm_committed_sp= ace > diff --git a/mm/nommu.c b/mm/nommu.c > index 2696b24..7695dc8 100644 > --- a/mm/nommu.c > +++ b/mm/nommu.c > @@ -1454,7 +1454,8 @@ int __vm_enough_memory(struct mm_struct *mm, long p= ages, int cap_sys_admin) > > =A0 =A0 =A0 =A0/* Don't let a single process grow too big: > =A0 =A0 =A0 =A0 =A0 leave 3% of the size of this process for other proces= ses */ > - =A0 =A0 =A0 allowed -=3D current->mm->total_vm / 32; > + =A0 =A0 =A0 if (mm) > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 allowed -=3D mm->total_vm / 32; > > =A0 =A0 =A0 =A0/* > =A0 =A0 =A0 =A0 * cast `allowed' as a signed long because vm_committed_sp= ace > diff --git a/mm/shmem.c b/mm/shmem.c > index d38d7e6..0ed0752 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -161,8 +161,8 @@ static inline struct shmem_sb_info *SHMEM_SB(struct s= uper_block *sb) > =A0*/ > =A0static inline int shmem_acct_size(unsigned long flags, loff_t size) > =A0{ > - =A0 =A0 =A0 return (flags & VM_ACCOUNT)? > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 security_vm_enough_memory(VM_ACCT(size)): 0= ; > + =A0 =A0 =A0 return (flags & VM_ACCOUNT) ? > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 security_vm_enough_memory_kern(VM_ACCT(size= )) : 0; > =A0} > > =A0static inline void shmem_unacct_size(unsigned long flags, loff_t size) > @@ -179,8 +179,8 @@ static inline void shmem_unacct_size(unsigned long fl= ags, loff_t size) > =A0*/ > =A0static inline int shmem_acct_block(unsigned long flags) > =A0{ > - =A0 =A0 =A0 return (flags & VM_ACCOUNT)? > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 0: security_vm_enough_memory(VM_ACCT(PAGE_C= ACHE_SIZE)); > + =A0 =A0 =A0 return (flags & VM_ACCOUNT) ? > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 0 : security_vm_enough_memory_kern(VM_ACCT(= PAGE_CACHE_SIZE)); > =A0} > > =A0static inline void shmem_unacct_blocks(unsigned long flags, long pages= ) > diff --git a/security/security.c b/security/security.c > index 255b085..c0acfa7 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -198,14 +198,23 @@ int security_settime(struct timespec *ts, struct ti= mezone *tz) > > =A0int security_vm_enough_memory(long pages) > =A0{ > + =A0 =A0 =A0 WARN_ON(current->mm =3D=3D NULL); > =A0 =A0 =A0 =A0return security_ops->vm_enough_memory(current->mm, pages); > =A0} > > =A0int security_vm_enough_memory_mm(struct mm_struct *mm, long pages) > =A0{ > + =A0 =A0 =A0 WARN_ON(mm =3D=3D NULL); > =A0 =A0 =A0 =A0return security_ops->vm_enough_memory(mm, pages); > =A0} > > +int security_vm_enough_memory_kern(long pages) > +{ > + =A0 =A0 =A0 /* If current->mm is a kernel thread then we will pass NULL= , > + =A0 =A0 =A0 =A0 =A0for this specific case that is fine */ > + =A0 =A0 =A0 return security_ops->vm_enough_memory(current->mm, pages); > +} > + > =A0int security_bprm_alloc(struct linux_binprm *bprm) > =A0{ > =A0 =A0 =A0 =A0return security_ops->bprm_alloc_security(bprm); > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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