[Devel] [PATCH hci-8.1 1/8] oracle/mm: fix VM_BUG_ON hit when preserving memory

[no-reply at sashiko.virtuozzo.com]

> From: Anthony Yznaga <anthony.yznaga at oracle.com>
> 
> copy_page_range_mt() is a stripped down version of copy_page_range().
> Unlike copy_page_range(), it is called during exec with the mmap read
> lock held on the outgoing mm. Assert that the mmap lock is held, and
> hold the write on the write_protect_seq seqcount_t section. The latter
> is needed to avoid a VM_BUG_ON in folio_needs_cow_for_dma().
> 
> Orabug: 37588319
> Signed-off-by: Anthony Yznaga <anthony.yznaga at oracle.com>
> Reviewed-by: Liam R. Howlett <liam.howlett at oracle.com>
> (cherry picked from commit b4c299d320c22ed30b03c7e665389c9870dd9bab)
> 
> Taken from Oracle linux-uek branch uek8/u2. Applied cleanly. Same
> Orabug as 90339648df65 ("oracle/mm: fix vma iterator misconfiguration
> that triggers VM_WARN_ONs"), which we already have; this is the second
> half of that pair.
> 
> Fixes: d674aa9506ea ("oracle/mm: use padata for copying page ranges in vma_dup()")
> https://virtuozzo.atlassian.net/browse/VSTOR-150231
> 
> Feature: oracle/mm: MADV_DOEXEC madvise() flag
> Assisted-by: LLM
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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