Messages in this thread | | | Subject | Re: [PATCH 1/2] tomoyo: Convert get_user_pages*() to pin_user_pages*() | From | John Hubbard <> | Date | Sat, 7 Nov 2020 01:04:50 -0800 |
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On 11/7/20 12:24 AM, Souptick Joarder wrote: > In 2019, we introduced pin_user_pages*() and now we are converting > get_user_pages*() to the new API as appropriate. [1] & [2] could > be referred for more information. This is case 5 as per document [1].
It turns out that Case 5 can be implemented via a better pattern, as long as we're just dealing with a page at a time, briefly:
lock_page() write to page's data unlock_page()
...which neatly synchronizes with writeback and other fs activities.
I was going to track down the Case 5's and do that [1].
+CC Jan and Matthew, to keep us on the straight and narrow, just in case I'm misunderstanding something.
[1] https://lore.kernel.org/r/e78fb7af-627b-ce80-275e-51f97f1f3168@nvidia.com
thanks, -- John Hubbard NVIDIA
> > [1] Documentation/core-api/pin_user_pages.rst > > [2] "Explicit pinning of user-space pages": > https://lwn.net/Articles/807108/ > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> > Cc: John Hubbard <jhubbard@nvidia.com> > --- > security/tomoyo/domain.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c > index dc4ecc0..bd748be 100644 > --- a/security/tomoyo/domain.c > +++ b/security/tomoyo/domain.c > @@ -914,7 +914,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos, > * (represented by bprm). 'current' is the process doing > * the execve(). > */ > - if (get_user_pages_remote(bprm->mm, pos, 1, > + if (pin_user_pages_remote(bprm->mm, pos, 1, > FOLL_FORCE, &page, NULL, NULL) <= 0) > return false; > #else > @@ -936,7 +936,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos, > } > /* Same with put_arg_page(page) in fs/exec.c */ > #ifdef CONFIG_MMU > - put_page(page); > + unpin_user_page(page); > #endif > return true; > } >
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