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Date: Tue, 16 Jun 2015 08:33:46 +0200 From: Michal Hocko <mhocko@...e.cz> To: Pali Rohár <pali.rohar@...il.com> Cc: Hans de Goede <hdegoede@...hat.com>, Darren Hart <dvhart@...radead.org>, Ben Skeggs <bskeggs@...hat.com>, Stuart Hayes <stuart_hayes@...l.com>, Matthew Garrett <mjg@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, platform-driver-x86@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: Re: Possible broken MM code in dell-laptop.c? On Mon 15-06-15 23:27:59, Pali Rohár wrote: > On Monday 15 June 2015 23:18:16 Michal Hocko wrote: > > On Sun 14-06-15 11:05:07, Pali Rohár wrote: > > > Hello, > > > > > > in drivers/platform/x86/dell-laptop.c is this part of code: > > > > > > static int __init dell_init(void) > > > { > > > ... > > > > > > /* > > > > > > * Allocate buffer below 4GB for SMI data--only 32-bit physical > > > addr * is passed to SMI handler. > > > */ > > > > > > bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32); > > > > [...] > > > > > buffer = page_address(bufferpage); > > > > [...] > > > > > fail_rfkill: > > > free_page((unsigned long)bufferpage); > > > > This one should be __free_page because it consumes struct page* and > > it is the proper counter part for alloc_page. free_page, just to > > make it confusing, consumes an address which has to be translated to > > a struct page. > > > > I have no idea why the API has been done this way and yeah, it is > > really confusing. > > > > [...] > > > > > static void __exit dell_exit(void) > > > { > > > ... > > > > > > free_page((unsigned long)buffer); > > So both, either: > > free_page((unsigned long)buffer); > > or > > __free_page(bufferpage); > > is correct? Yes. Although I would use __free_page variant as both seem to be globally visible. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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