Messages in this thread | | | Subject | Re: [PATCH v7 1/7] mm: pass task and mm to do_madvise | From | Vlastimil Babka <> | Date | Thu, 5 Mar 2020 16:48:12 +0100 |
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On 3/2/20 8:36 PM, Minchan Kim wrote: > In upcoming patches, do_madvise will be called from external process > context so we shouldn't asssume "current" is always hinted process's > task_struct.
> Furthermore, we couldn't access mm_struct via task->mm > once it's verified by access_mm which will be introduced in next > patch[1].
I would suggest to replace with:
Furthermore, we must not access mm_struct via task->mm, but obtain it via access_mm() once (in the following patch) and only use that pointer [1], so pass it to do_madvise() as well. Note the vma->vm_mm pointers are safe, so we can use them further down the call stack.
> And let's pass *current* and current->mm as arguments of > do_madvise so it shouldn't change existing behavior but prepare > next patch to make review easy. > > Note: io_madvise pass NULL as target_task argument of do_madvise > because it couldn't know who is target.
can't
> [1] http://lore.kernel.org/r/CAG48ez27=pwm5m_N_988xT1huO7g7h6arTQL44zev6TD-h-7Tg@mail.gmail.com > > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Jann Horn <jannh@google.com> > Reviewed-by: Suren Baghdasaryan <surenb@google.com> > Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Nit:
> @@ -676,7 +677,6 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, > if (nr_swap) { > if (current->mm == mm) > sync_mm_rss(mm); > - > add_mm_counter(mm, MM_SWAPENTS, nr_swap); > } > arch_leave_lazy_mmu_mode();
This looks stray and unrelated.
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