Re: [PATCH v2 0/4] scsi: replace __get_free_pages() with kmalloc()
Mike Rapoport <[email protected]> Mon, 20 Jul 2026 15:43:49 +0300
| Newsgroups | org.kernel.vger.target-devel,org.kernel.vger.linux-kernel,org.kernel.vger.linux-scsi,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
Gentle ping. On Sat, Jul 04, 2026 at 09:13:33AM +0300, Mike Rapoport (Microsoft) wrote: > This is a (small) part of larger work of replacing page allocator calls > with kmalloc. > > My initial intention a few month ago was to remove ugly casts [1], but then > willy pointed out that Linus objected to something like this [2] and it > looks like more than a decade old technical debt. > > Largely, anything that doesn't need struct page (or a memdesc in the > future) should just use kmalloc() or kvmalloc() to allocate memory. > kmalloc() guarantees alignment, physical contiguity and working > virt_to_phys() and beside nicer API that returns void * on alloc and > doesn't require to know the allocation size on free, kmalloc() provides > better debugging capabilities than page allocator. > > Another thing is that touching these allocation sites gives the reviewers > opportunity to see if a PAGE_SIZE buffer is actually needed or maybe > another size is appropriate. > > For larger allocations that don't need physically contiguous memory > kvmalloc() can be a better option that __get_free_pages() because under > memory pressure it's is easier to allocate several order-0 pages than a > physically contiguous chunk with the same number of pages. > > And last, but not least, removing needless calls to page allocator should > help with memdesc (aka project folio) conversion. There will be way less > places to audit to see if the user was actually using struct page. > > Also in git: > https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git gfp-to-kmalloc/scsi > > [1] https://lore.kernel.org/all/[email protected]/ > [2] https://lore.kernel.org/all/CA+55aFwp4iy4rtX2gE2WjBGFL=NxMVnoFeHqYa2j1dYOMMGqxg@mail.gmail.com/ > > --- > v2 changes: > * replace GFP_ATOMIC with GFP_NOIO in ipr driver > > v1: https://patch.msgid.link/[email protected] > > --- > Mike Rapoport (Microsoft) (4): > scsi: target: file: use kmalloc() to allocate temporary protection buffer > scsi: proc: use kmalloc() in proc writers > scsi: ipr: use kmalloc() to allocate IPR dump buffer memory > scsi: sym53c8xx_2: replace __get_free_pages() with kmalloc() > > drivers/scsi/ipr.c | 4 ++-- > drivers/scsi/scsi_devinfo.c | 5 +++-- > drivers/scsi/scsi_proc.c | 9 +++++---- > drivers/scsi/sym53c8xx_2/sym_hipd.h | 4 ++-- > drivers/target/target_core_file.c | 4 ++-- > 5 files changed, 14 insertions(+), 12 deletions(-) > --- > base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 > change-id: 20260611-b4-scsi-d0b0eb4895f4 > > -- > Sincerely yours, > Mike. > -- Sincerely yours, Mike.