Messages in this thread | | | Subject | Re: [RFC PATCH] memalloc_noio: update the comment to make it cleaner | From | Xiubo Li <> | Date | Wed, 18 Sep 2019 16:02:52 +0800 |
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On 2019/9/18 15:25, Michal Hocko wrote: > On Wed 18-09-19 04:58:20, xiubli@redhat.com wrote: >> From: Xiubo Li <xiubli@redhat.com> >> >> The GFP_NOIO means all further allocations will implicitly drop >> both __GFP_IO and __GFP_FS flags and so they are safe for both the >> IO critical section and the the critical section from the allocation >> recursion point of view. Not only the __GFP_IO, which a bit confusing >> when reading the code or using the save/restore pair. > Historically GFP_NOIO has always implied GFP_NOFS as well. I can imagine > that this might come as an surprise for somebody not familiar with the > code though.
Yeah, it true.
> I am wondering whether your update of the documentation > would be better off at __GFP_FS, __GFP_IO resp. GFP_NOFS, GFP_NOIO level. > This interface is simply a way to set a scoped NO{IO,FS} context.
The "Documentation/core-api/gfp_mask-from-fs-io.rst" is already very detail about them all.
This fixing just means to make sure that it won't surprise someone who is having a quickly through some code and not familiar much about the detail. It may make not much sense ?
Thanks, BRs Xiubo
>> Signed-off-by: Xiubo Li <xiubli@redhat.com> >> --- >> include/linux/sched/mm.h | 9 +++++---- >> 1 file changed, 5 insertions(+), 4 deletions(-) >> >> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h >> index 4a7944078cc3..9bdc97e52de1 100644 >> --- a/include/linux/sched/mm.h >> +++ b/include/linux/sched/mm.h >> @@ -211,10 +211,11 @@ static inline void fs_reclaim_release(gfp_t gfp_mask) { } >> * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope. >> * >> * This functions marks the beginning of the GFP_NOIO allocation scope. >> - * All further allocations will implicitly drop __GFP_IO flag and so >> - * they are safe for the IO critical section from the allocation recursion >> - * point of view. Use memalloc_noio_restore to end the scope with flags >> - * returned by this function. >> + * All further allocations will implicitly drop __GFP_IO and __GFP_FS >> + * flags and so they are safe for both the IO critical section and the >> + * the critical section from the allocation recursion point of view. Use >> + * memalloc_noio_restore to end the scope with flags returned by this >> + * function. >> * >> * This function is safe to be used from any context. >> */ >> -- >> 2.21.0
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