From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "jannh@google.com" <jannh@google.com>
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Subject: Re: [PATCH v2 1/7] modules: Create rlimit for module space
Date: Sat, 13 Oct 2018 00:04:14 +0000 [thread overview]
Message-ID: <657e6d0ada18e8ca0350bc6b3a80c49b3c0b341c.camel@intel.com> (raw)
In-Reply-To: <CAG48ez0XfGFAWDYa75COMPCsKqqGfBFOtcNuGD4_dubGf2YeAQ@mail.gmail.com>
On Fri, 2018-10-12 at 19:22 +0200, Jann Horn wrote:
> On Fri, Oct 12, 2018 at 7:04 PM Edgecombe, Rick P
> <rick.p.edgecombe@intel.com> wrote:
> > On Fri, 2018-10-12 at 02:35 +0200, Jann Horn wrote:
> > > Why all the rbtree stuff instead of stashing a pointer in struct
> > > vmap_area, or something like that?
> >
> > Since the tracking was not for all vmalloc usage, the intention was to not
> > bloat
> > the structure for other usages likes stacks. I thought usually there
> > wouldn't be
> > nearly as much module space allocations as there would be kernel stacks, but
> > I
> > didn't do any actual measurements on the tradeoffs.
>
> I imagine that one extra pointer in there - pointing to your struct
> mod_alloc_user - would probably not be terrible. 8 bytes more per
> kernel stack shouldn't be so bad?
I looked into this and it starts to look a little messy. The nommu.c version of
vmalloc doesn't use or expose access to vmap_area or vm_struct. So it starts to
look like a bunch of IFDEFs to remove the rlimit in the nommu case or making a
stand in that maintains pretend vm struct's in nommu.c. I had actually
previously tried to at least pull the allocations size from vmalloc structs, but it broke on nommu.
Thought I would check back and see. How important do you think this is?
next prev parent reply other threads:[~2018-10-13 7:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 23:31 [PATCH v2 0/7] Rlimit for module space Rick Edgecombe
2018-10-11 23:31 ` [PATCH v2 1/7] modules: Create rlimit " Rick Edgecombe
2018-10-12 0:35 ` Jann Horn
2018-10-12 17:04 ` Edgecombe, Rick P
2018-10-12 17:22 ` Jann Horn
2018-10-13 0:04 ` Edgecombe, Rick P [this message]
2018-10-13 0:09 ` Jann Horn
2018-10-23 11:32 ` Michal Hocko
2018-10-12 18:23 ` Jann Horn
2018-10-11 23:31 ` [PATCH v2 2/7] x86/modules: Add rlimit checking for x86 modules Rick Edgecombe
2018-10-11 23:31 ` [PATCH v2 3/7] arm/modules: Add rlimit checking for arm modules Rick Edgecombe
2018-10-11 23:31 ` [PATCH v2 4/7] arm64/modules: Add rlimit checking for arm64 modules Rick Edgecombe
2018-10-11 23:47 ` Dave Hansen
2018-10-12 14:32 ` Jessica Yu
2018-10-12 22:01 ` Edgecombe, Rick P
2018-10-12 22:54 ` Edgecombe, Rick P
2018-10-11 23:31 ` [PATCH v2 5/7] mips/modules: Add rlimit checking for mips modules Rick Edgecombe
2018-10-11 23:31 ` [PATCH v2 6/7] sparc/modules: Add rlimit for sparc modules Rick Edgecombe
2018-10-11 23:31 ` [PATCH v2 7/7] s390/modules: Add rlimit checking for s390 modules Rick Edgecombe
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