Messages in this thread | | | Date | Tue, 24 Nov 2015 15:12:58 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH 2/3] zram: try vmalloc() after kmalloc() |
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[..] > static void *zcomp_lz4_create(void) > { > - return kzalloc(LZ4_MEM_COMPRESS, GFP_KERNEL); > + void *ret; > + > + /* > + * This function could be called in swapout/fs write path > + * so we couldn't use GFP_FS|IO. And it assumes we already > + * have at least one stream in zram initialization so we > + * don't do best effort to allocate more stream in here. > + * A default stream will work well without further multiple > + * stream. That's why we use __GFP_NORETRY|NOWARN|NOMEMALLOC. > + */ > + ret = kzalloc(LZ4_MEM_COMPRESS, > + __GFP_NORETRY|__GFP_NOWARN|__GFP_NOMEMALLOC); > + if (!ret) > + ret = __vmalloc(LZ4_MEM_COMPRESS, > + __GFP_NORETRY|__GFP_NOWARN| > + __GFP_NOMEMALLOC|__GFP_ZERO, > + PAGE_KERNEL); > + return ret; > } [..]
so this change is still questionable. is there a real value in having a vmalloc() fallback in the middle of allocations sequence:
zstrm = kmalloc(sizeof(*zstrm), GFP_NOIO); ^^^ ok, can fail here
zstrm->zstrm->private = comp->backend->create(); ^^^ kzalloc() and vmalloc() fallback ??
zstrm->buffer = (void *)__get_free_pages(GFP_NOIO | __GFP_ZERO, 1); ^^^ can fail here again.
can you please comment on this?
and I'd prefer it to be a bit different -- use likely path first and avoid an assignment in unlikely path. ... and add GFP_NOIO to both kzalloc() and __vmalloc().
and there is no __GFP_HIGHMEM in __vmalloc() call?
something like this:
---
ret = kzalloc(LZ4_MEM_COMPRESS, GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC); if (ret) return ret;
return __vmalloc(LZ4_MEM_COMPRESS, GFP_NOIO | __GFP_NOWARN | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
-ss
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